Prereq: "3.5.22"
diff -ur --new-file /var/tmp/postfix-3.5.22/src/global/mail_version.h ./src/global/mail_version.h
--- /var/tmp/postfix-3.5.22/src/global/mail_version.h	2023-11-01 12:49:38.000000000 -0400
+++ ./src/global/mail_version.h	2023-12-22 13:56:18.000000000 -0500
@@ -20,8 +20,8 @@
   * Patches change both the patchlevel and the release date. Snapshots have no
   * patchlevel; they change the release date only.
   */
-#define MAIL_RELEASE_DATE	"20231101"
-#define MAIL_VERSION_NUMBER	"3.5.22"
+#define MAIL_RELEASE_DATE	"20231222"
+#define MAIL_VERSION_NUMBER	"3.5.23"
 
 #ifdef SNAPSHOT
 #define MAIL_VERSION_DATE	"-" MAIL_RELEASE_DATE
diff -ur --new-file /var/tmp/postfix-3.5.22/HISTORY ./HISTORY
--- /var/tmp/postfix-3.5.22/HISTORY	2023-10-31 14:52:28.000000000 -0400
+++ ./HISTORY	2023-12-22 13:55:36.000000000 -0500
@@ -25399,3 +25399,17 @@
 	delimiter. Fixed by restoring Postfix 2.10 behavior to use
 	a configured recipient delimiter value. Reported by Tod
 	A. Sandman. Files: proto/postconf.proto, local/local_expand.c.
+
+20231221
+
+	Security: with "smtpd_forbid_bare_newline = yes" (default
+	"no" for Postfix < 3.9), reply with "Error: bare <LF>
+	received" and disconnect when an SMTP client sends a line
+	ending in <LF>, violating the RFC 5321 requirement that
+	lines must end in <CR><LF>. This prevents SMTP smuggling
+	attacks that target a recipient at a Postfix server. For
+	backwards compatibility, local clients are excluded by
+	default with "smtpd_forbid_bare_newline_exclusions =
+	$mynetworks". Files: mantools/postlink, proto/postconf.proto,
+	global/mail_params.h, global/smtp_stream.c, global/smtp_stream.h,
+	smtpd/smtpd.c.
diff -ur --new-file /var/tmp/postfix-3.5.22/RELEASE_NOTES ./RELEASE_NOTES
--- /var/tmp/postfix-3.5.22/RELEASE_NOTES	2023-06-05 17:38:31.000000000 -0400
+++ ./RELEASE_NOTES	2023-12-22 13:57:33.000000000 -0500
@@ -25,6 +25,31 @@
 the software under the license of their choice. Those who are more
 comfortable with the IPL can continue with that license.
 
+Major changes with Postfix 3.5.23
+=================================
+
+Security: the Postfix SMTP server optionally disconnects a remote
+SMTP client that sends a 'bare newline' line ending in SMTP. This
+prevents an SMTP smuggling attack on recipients at a Postfix server.
+For background, see https://www.postfix.org/smtp-smuggling.html
+
+Sites concerned about SMTP smuggling attacks should enable this
+feature in Internet-facing Postfix servers. For compatibility with
+non-standard clients, Postfix by default excludes clients in
+mynetworks from this countermeasure.
+
+The recommended settings are:
+
+    # Optionally disconnect remote SMTP clients that send bare newlines,
+    # but allow local clients with non-standard SMTP implementations
+    # such as netcat, fax machines, or load balancer health checks.
+    #
+    smtpd_forbid_bare_newline = no
+    smtpd_forbid_bare_newline_exclusions = $mynetworks
+
+This feature is back-ported from Postfix 3.9, with the difference
+that "smtpd_forbid_bare_newline = no" by default.
+  
 Major changes with Postfix 3.5.20
 =================================
 
diff -ur --new-file /var/tmp/postfix-3.5.22/html/postconf.5.html ./html/postconf.5.html
--- /var/tmp/postfix-3.5.22/html/postconf.5.html	2023-11-01 12:43:47.000000000 -0400
+++ ./html/postconf.5.html	2023-12-22 13:58:15.000000000 -0500
@@ -15049,6 +15049,65 @@
 
 </DD>
 
+<DT><b><a name="smtpd_forbid_bare_newline">smtpd_forbid_bare_newline</a>
+(default: Postfix &lt; 3.9: no)</b></DT><DD>
+
+<p> Reply with "Error: bare &lt;LF&gt; received" and disconnect
+when a remote SMTP client sends a line ending in &lt;LF&gt;, violating
+the <a href="http://tools.ietf.org/html/rfc5321">RFC 5321</a> requirement that lines must end in &lt;CR&gt;&lt;LF&gt;.
+This feature is disbled by default with Postfix &lt; 3.9. Use
+<a href="postconf.5.html#smtpd_forbid_bare_newline_exclusions">smtpd_forbid_bare_newline_exclusions</a> to exclude non-standard clients
+such as netcat. Specify "<a href="postconf.5.html#smtpd_forbid_bare_newline">smtpd_forbid_bare_newline</a> = no" to disable
+(not recommended for an Internet-connected MTA). </p>
+
+<p> See <a href="https://www.postfix.org/smtp-smuggling.html">
+https://www.postfix.org/smtp-smuggling.html</a> for details.
+
+<p> Example: </p>
+
+<blockquote>
+<pre>
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+<a href="postconf.5.html#smtpd_forbid_bare_newline">smtpd_forbid_bare_newline</a> = yes
+<a href="postconf.5.html#smtpd_forbid_bare_newline_exclusions">smtpd_forbid_bare_newline_exclusions</a> = $<a href="postconf.5.html#mynetworks">mynetworks</a>
+</pre>
+</blockquote>
+
+<p> This feature is available in Postfix &ge; 3.9, 3.8.4, 3.7.9,
+3.6.13, and 3.5.23. </p>
+
+
+</DD>
+
+<DT><b><a name="smtpd_forbid_bare_newline_exclusions">smtpd_forbid_bare_newline_exclusions</a>
+(default: $<a href="postconf.5.html#mynetworks">mynetworks</a>)</b></DT><DD>
+
+<p> Exclude the specified clients from <a href="postconf.5.html#smtpd_forbid_bare_newline">smtpd_forbid_bare_newline</a>
+enforcement. It uses the same syntax and parent-domain matching
+behavior as <a href="postconf.5.html#mynetworks">mynetworks</a>. </p>
+
+<p> Example: </p>
+
+<blockquote>
+<pre>
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+<a href="postconf.5.html#smtpd_forbid_bare_newline">smtpd_forbid_bare_newline</a> = yes
+<a href="postconf.5.html#smtpd_forbid_bare_newline_exclusions">smtpd_forbid_bare_newline_exclusions</a> = $<a href="postconf.5.html#mynetworks">mynetworks</a>
+</pre>
+</blockquote>
+
+<p> This feature is available in Postfix &ge; 3.9, 3.8.4, 3.7.9,
+3.6.13, and 3.5.23. </p>
+
+
+</DD>
+
 <DT><b><a name="smtpd_forbid_unauth_pipelining">smtpd_forbid_unauth_pipelining</a>
 (default: Postfix &ge; 3.9: yes)</b></DT><DD>
 
diff -ur --new-file /var/tmp/postfix-3.5.22/html/smtpd.8.html ./html/smtpd.8.html
--- /var/tmp/postfix-3.5.22/html/smtpd.8.html	2023-11-01 12:43:29.000000000 -0400
+++ ./html/smtpd.8.html	2023-12-22 13:58:15.000000000 -0500
@@ -612,12 +612,12 @@
               tialization functions.
 
 <b>OBSOLETE STARTTLS CONTROLS</b>
-       The following configuration parameters  exist  for  compatibility  with
-       Postfix  versions  before  2.3.  Support for these will be removed in a
+       The  following  configuration  parameters  exist for compatibility with
+       Postfix versions before 2.3. Support for these will  be  removed  in  a
        future release.
 
        <b><a href="postconf.5.html#smtpd_use_tls">smtpd_use_tls</a> (no)</b>
-              Opportunistic TLS: announce  STARTTLS  support  to  remote  SMTP
+              Opportunistic  TLS:  announce  STARTTLS  support  to remote SMTP
               clients, but do not require that clients use TLS encryption.
 
        <b><a href="postconf.5.html#smtpd_enforce_tls">smtpd_enforce_tls</a> (no)</b>
@@ -625,92 +625,92 @@
               and require that clients use TLS encryption.
 
        <b><a href="postconf.5.html#smtpd_tls_cipherlist">smtpd_tls_cipherlist</a> (empty)</b>
-              Obsolete Postfix &lt; 2.3 control for the Postfix SMTP  server  TLS
+              Obsolete  Postfix  &lt; 2.3 control for the Postfix SMTP server TLS
               cipher list.
 
 <b>SMTPUTF8 CONTROLS</b>
        Preliminary SMTPUTF8 support is introduced with Postfix 3.0.
 
        <b><a href="postconf.5.html#smtputf8_enable">smtputf8_enable</a> (yes)</b>
-              Enable  preliminary SMTPUTF8 support for the protocols described
+              Enable preliminary SMTPUTF8 support for the protocols  described
               in <a href="http://tools.ietf.org/html/rfc6531">RFC 6531</a>..6533.
 
        <b><a href="postconf.5.html#strict_smtputf8">strict_smtputf8</a> (no)</b>
               Enable stricter enforcement of the SMTPUTF8 protocol.
 
        <b><a href="postconf.5.html#smtputf8_autodetect_classes">smtputf8_autodetect_classes</a> (sendmail, verify)</b>
-              Detect that a message requires SMTPUTF8 support for  the  speci-
+              Detect  that  a message requires SMTPUTF8 support for the speci-
               fied mail origin classes.
 
        Available in Postfix version 3.2 and later:
 
        <b><a href="postconf.5.html#enable_idna2003_compatibility">enable_idna2003_compatibility</a> (no)</b>
-              Enable   'transitional'   compatibility   between  IDNA2003  and
-              IDNA2008, when converting UTF-8 domain names to/from  the  ASCII
+              Enable  'transitional'  compatibility   between   IDNA2003   and
+              IDNA2008,  when  converting UTF-8 domain names to/from the ASCII
               form that is used for DNS lookups.
 
 <b>VERP SUPPORT CONTROLS</b>
-       With  VERP  style delivery, each recipient of a message receives a cus-
-       tomized copy of the message with his/her own recipient address  encoded
+       With VERP style delivery, each recipient of a message receives  a  cus-
+       tomized  copy of the message with his/her own recipient address encoded
        in the envelope sender address.  The <a href="VERP_README.html">VERP_README</a> file describes config-
-       uration and operation details of Postfix support for variable  envelope
-       return  path addresses.  VERP style delivery is requested with the SMTP
-       XVERP command or with the "sendmail  -V"  command-line  option  and  is
+       uration  and operation details of Postfix support for variable envelope
+       return path addresses.  VERP style delivery is requested with the  SMTP
+       XVERP  command  or  with  the  "sendmail -V" command-line option and is
        available in Postfix version 1.1 and later.
 
        <b><a href="postconf.5.html#default_verp_delimiters">default_verp_delimiters</a> (+=)</b>
               The two default VERP delimiter characters.
 
        <b><a href="postconf.5.html#verp_delimiter_filter">verp_delimiter_filter</a> (-=+)</b>
-              The  characters  Postfix accepts as VERP delimiter characters on
+              The characters Postfix accepts as VERP delimiter  characters  on
               the Postfix <a href="sendmail.1.html"><b>sendmail</b>(1)</a> command line and in SMTP commands.
 
        Available in Postfix version 1.1 and 2.0:
 
        <b><a href="postconf.5.html#authorized_verp_clients">authorized_verp_clients</a> ($<a href="postconf.5.html#mynetworks">mynetworks</a>)</b>
-              What remote SMTP clients are allowed to specify the  XVERP  com-
+              What  remote  SMTP clients are allowed to specify the XVERP com-
               mand.
 
        Available in Postfix version 2.1 and later:
 
        <b><a href="postconf.5.html#smtpd_authorized_verp_clients">smtpd_authorized_verp_clients</a> ($<a href="postconf.5.html#authorized_verp_clients">authorized_verp_clients</a>)</b>
-              What  remote  SMTP clients are allowed to specify the XVERP com-
+              What remote SMTP clients are allowed to specify the  XVERP  com-
               mand.
 
 <b>TROUBLE SHOOTING CONTROLS</b>
-       The <a href="DEBUG_README.html">DEBUG_README</a> document describes how to debug parts of  the  Postfix
-       mail  system.  The  methods  vary from making the software log a lot of
+       The  <a href="DEBUG_README.html">DEBUG_README</a>  document describes how to debug parts of the Postfix
+       mail system. The methods vary from making the software  log  a  lot  of
        detail, to running some daemon processes under control of a call tracer
        or debugger.
 
        <b><a href="postconf.5.html#debug_peer_level">debug_peer_level</a> (2)</b>
-              The  increment  in verbose logging level when a remote client or
+              The increment in verbose logging level when a remote  client  or
               server matches a pattern in the <a href="postconf.5.html#debug_peer_list">debug_peer_list</a> parameter.
 
        <b><a href="postconf.5.html#debug_peer_list">debug_peer_list</a> (empty)</b>
-              Optional list of remote client or  server  hostname  or  network
+              Optional  list  of  remote  client or server hostname or network
               address  patterns  that  cause  the  verbose  logging  level  to
               increase by the amount specified in $<a href="postconf.5.html#debug_peer_level">debug_peer_level</a>.
 
        <b><a href="postconf.5.html#error_notice_recipient">error_notice_recipient</a> (postmaster)</b>
-              The recipient of postmaster notifications  about  mail  delivery
+              The  recipient  of  postmaster notifications about mail delivery
               problems that are caused by policy, resource, software or proto-
               col errors.
 
        <b><a href="postconf.5.html#internal_mail_filter_classes">internal_mail_filter_classes</a> (empty)</b>
-              What  categories  of  Postfix-generated  mail  are  subject   to
-              before-queue    content    inspection    by   <a href="postconf.5.html#non_smtpd_milters">non_smtpd_milters</a>,
+              What   categories  of  Postfix-generated  mail  are  subject  to
+              before-queue   content    inspection    by    <a href="postconf.5.html#non_smtpd_milters">non_smtpd_milters</a>,
               <a href="postconf.5.html#header_checks">header_checks</a> and <a href="postconf.5.html#body_checks">body_checks</a>.
 
        <b><a href="postconf.5.html#notify_classes">notify_classes</a> (resource, software)</b>
               The list of error classes that are reported to the postmaster.
 
        <b><a href="postconf.5.html#smtpd_reject_footer">smtpd_reject_footer</a> (empty)</b>
-              Optional information that is appended after  each  Postfix  SMTP
+              Optional  information  that  is appended after each Postfix SMTP
               server 4XX or 5XX response.
 
        <b><a href="postconf.5.html#soft_bounce">soft_bounce</a> (no)</b>
-              Safety  net to keep mail queued that would otherwise be returned
+              Safety net to keep mail queued that would otherwise be  returned
               to the sender.
 
        Available in Postfix version 2.1 and later:
@@ -721,109 +721,109 @@
        Available in Postfix version 2.10 and later:
 
        <b><a href="postconf.5.html#smtpd_log_access_permit_actions">smtpd_log_access_permit_actions</a> (empty)</b>
-              Enable  logging  of  the  named  "permit" actions in SMTP server
-              access lists (by default, the SMTP server logs "reject"  actions
+              Enable logging of the named  "permit"  actions  in  SMTP  server
+              access  lists (by default, the SMTP server logs "reject" actions
               but not "permit" actions).
 
 <b>KNOWN VERSUS UNKNOWN RECIPIENT CONTROLS</b>
-       As  of  Postfix  version  2.0, the SMTP server rejects mail for unknown
+       As of Postfix version 2.0, the SMTP server  rejects  mail  for  unknown
        recipients. This prevents the mail queue from clogging up with undeliv-
-       erable  MAILER-DAEMON messages. Additional information on this topic is
+       erable MAILER-DAEMON messages. Additional information on this topic  is
        in the <a href="LOCAL_RECIPIENT_README.html">LOCAL_RECIPIENT_README</a> and <a href="ADDRESS_CLASS_README.html">ADDRESS_CLASS_README</a> documents.
 
        <b><a href="postconf.5.html#show_user_unknown_table_name">show_user_unknown_table_name</a> (yes)</b>
-              Display the name of the recipient table in  the  "User  unknown"
+              Display  the  name  of the recipient table in the "User unknown"
               responses.
 
        <b><a href="postconf.5.html#canonical_maps">canonical_maps</a> (empty)</b>
-              Optional  address  mapping lookup tables for message headers and
+              Optional address mapping lookup tables for message  headers  and
               envelopes.
 
        <b><a href="postconf.5.html#recipient_canonical_maps">recipient_canonical_maps</a> (empty)</b>
-              Optional address mapping lookup tables for envelope  and  header
+              Optional  address  mapping lookup tables for envelope and header
               recipient addresses.
 
        <b><a href="postconf.5.html#sender_canonical_maps">sender_canonical_maps</a> (empty)</b>
-              Optional  address  mapping lookup tables for envelope and header
+              Optional address mapping lookup tables for envelope  and  header
               sender addresses.
 
        Parameters concerning known/unknown local recipients:
 
        <b><a href="postconf.5.html#mydestination">mydestination</a> ($<a href="postconf.5.html#myhostname">myhostname</a>, localhost.$<a href="postconf.5.html#mydomain">mydomain</a>, localhost)</b>
-              The list of domains that are delivered via the  $<a href="postconf.5.html#local_transport">local_transport</a>
+              The  list of domains that are delivered via the $<a href="postconf.5.html#local_transport">local_transport</a>
               mail delivery transport.
 
        <b><a href="postconf.5.html#inet_interfaces">inet_interfaces</a> (all)</b>
-              The  network  interface addresses that this mail system receives
+              The network interface addresses that this mail  system  receives
               mail on.
 
        <b><a href="postconf.5.html#proxy_interfaces">proxy_interfaces</a> (empty)</b>
-              The network interface addresses that this mail  system  receives
+              The  network  interface addresses that this mail system receives
               mail on by way of a proxy or network address translation unit.
 
        <b><a href="postconf.5.html#inet_protocols">inet_protocols</a> (all)</b>
-              The  Internet  protocols Postfix will attempt to use when making
+              The Internet protocols Postfix will attempt to use  when  making
               or accepting connections.
 
        <b><a href="postconf.5.html#local_recipient_maps">local_recipient_maps</a> (<a href="proxymap.8.html">proxy</a>:unix:passwd.byname $<a href="postconf.5.html#alias_maps">alias_maps</a>)</b>
               Lookup tables with all names or addresses of local recipients: a
-              recipient  address  is local when its domain matches $<a href="postconf.5.html#mydestination">mydestina</a>-
+              recipient address is local when its domain  matches  $<a href="postconf.5.html#mydestination">mydestina</a>-
               <a href="postconf.5.html#mydestination">tion</a>, $<a href="postconf.5.html#inet_interfaces">inet_interfaces</a> or $<a href="postconf.5.html#proxy_interfaces">proxy_interfaces</a>.
 
        <b><a href="postconf.5.html#unknown_local_recipient_reject_code">unknown_local_recipient_reject_code</a> (550)</b>
               The numerical Postfix SMTP server response code when a recipient
-              address  is local, and $<a href="postconf.5.html#local_recipient_maps">local_recipient_maps</a> specifies a list of
+              address is local, and $<a href="postconf.5.html#local_recipient_maps">local_recipient_maps</a> specifies a list  of
               lookup tables that does not match the recipient.
 
        Parameters concerning known/unknown recipients of relay destinations:
 
        <b><a href="postconf.5.html#relay_domains">relay_domains</a> (Postfix</b> &gt;<b>= 3.0: empty, Postfix</b> &lt; <b>3.0: $<a href="postconf.5.html#mydestination">mydestination</a>)</b>
-              What destination domains (and subdomains  thereof)  this  system
+              What  destination  domains  (and subdomains thereof) this system
               will relay mail to.
 
        <b><a href="postconf.5.html#relay_recipient_maps">relay_recipient_maps</a> (empty)</b>
-              Optional  lookup  tables with all valid addresses in the domains
+              Optional lookup tables with all valid addresses in  the  domains
               that match $<a href="postconf.5.html#relay_domains">relay_domains</a>.
 
        <b><a href="postconf.5.html#unknown_relay_recipient_reject_code">unknown_relay_recipient_reject_code</a> (550)</b>
-              The numerical Postfix SMTP server reply code  when  a  recipient
-              address  matches $<a href="postconf.5.html#relay_domains">relay_domains</a>, and <a href="postconf.5.html#relay_recipient_maps">relay_recipient_maps</a> speci-
-              fies a list of lookup tables that does not match  the  recipient
+              The  numerical  Postfix  SMTP server reply code when a recipient
+              address matches $<a href="postconf.5.html#relay_domains">relay_domains</a>, and <a href="postconf.5.html#relay_recipient_maps">relay_recipient_maps</a>  speci-
+              fies  a  list of lookup tables that does not match the recipient
               address.
 
-       Parameters   concerning   known/unknown  recipients  in  virtual  alias
+       Parameters  concerning  known/unknown  recipients  in   virtual   alias
        domains:
 
        <b><a href="postconf.5.html#virtual_alias_domains">virtual_alias_domains</a> ($<a href="postconf.5.html#virtual_alias_maps">virtual_alias_maps</a>)</b>
-              Postfix is final destination for the specified list  of  virtual
-              alias  domains,  that  is,  domains  for which all addresses are
+              Postfix  is  final destination for the specified list of virtual
+              alias domains, that is, domains  for  which  all  addresses  are
               aliased to addresses in other local or remote domains.
 
        <b><a href="postconf.5.html#virtual_alias_maps">virtual_alias_maps</a> ($<a href="postconf.5.html#virtual_maps">virtual_maps</a>)</b>
-              Optional lookup tables that alias  specific  mail  addresses  or
+              Optional  lookup  tables  that  alias specific mail addresses or
               domains to other local or remote address.
 
        <b><a href="postconf.5.html#unknown_virtual_alias_reject_code">unknown_virtual_alias_reject_code</a> (550)</b>
-              The  Postfix  SMTP  server  reply  code when a recipient address
-              matches $<a href="postconf.5.html#virtual_alias_domains">virtual_alias_domains</a>, and  $<a href="postconf.5.html#virtual_alias_maps">virtual_alias_maps</a>  speci-
-              fies  a  list of lookup tables that does not match the recipient
+              The Postfix SMTP server reply  code  when  a  recipient  address
+              matches  $<a href="postconf.5.html#virtual_alias_domains">virtual_alias_domains</a>,  and $<a href="postconf.5.html#virtual_alias_maps">virtual_alias_maps</a> speci-
+              fies a list of lookup tables that does not match  the  recipient
               address.
 
        Parameters  concerning  known/unknown  recipients  in  virtual  mailbox
        domains:
 
        <b><a href="postconf.5.html#virtual_mailbox_domains">virtual_mailbox_domains</a> ($<a href="postconf.5.html#virtual_mailbox_maps">virtual_mailbox_maps</a>)</b>
-              Postfix  is final destination for the specified list of domains;
-              mail is  delivered  via  the  $<a href="postconf.5.html#virtual_transport">virtual_transport</a>  mail  delivery
+              Postfix is final destination for the specified list of  domains;
+              mail  is  delivered  via  the  $<a href="postconf.5.html#virtual_transport">virtual_transport</a>  mail delivery
               transport.
 
        <b><a href="postconf.5.html#virtual_mailbox_maps">virtual_mailbox_maps</a> (empty)</b>
-              Optional  lookup  tables with all valid addresses in the domains
+              Optional lookup tables with all valid addresses in  the  domains
               that match $<a href="postconf.5.html#virtual_mailbox_domains">virtual_mailbox_domains</a>.
 
        <b><a href="postconf.5.html#unknown_virtual_mailbox_reject_code">unknown_virtual_mailbox_reject_code</a> (550)</b>
-              The Postfix SMTP server reply  code  when  a  recipient  address
-              matches   $<a href="postconf.5.html#virtual_mailbox_domains">virtual_mailbox_domains</a>,   and  $<a href="postconf.5.html#virtual_mailbox_maps">virtual_mailbox_maps</a>
+              The  Postfix  SMTP  server  reply  code when a recipient address
+              matches  $<a href="postconf.5.html#virtual_mailbox_domains">virtual_mailbox_domains</a>,   and   $<a href="postconf.5.html#virtual_mailbox_maps">virtual_mailbox_maps</a>
               specifies a list of lookup tables that does not match the recip-
               ient address.
 
@@ -832,7 +832,7 @@
        control client request rates.
 
        <b><a href="postconf.5.html#line_length_limit">line_length_limit</a> (2048)</b>
-              Upon input, long lines are chopped up into  pieces  of  at  most
+              Upon  input,  long  lines  are chopped up into pieces of at most
               this length; upon delivery, long lines are reconstructed.
 
        <b><a href="postconf.5.html#queue_minfree">queue_minfree</a> (0)</b>
@@ -840,58 +840,58 @@
               tem that is needed to receive mail.
 
        <b><a href="postconf.5.html#message_size_limit">message_size_limit</a> (10240000)</b>
-              The maximal size in  bytes  of  a  message,  including  envelope
+              The  maximal  size  in  bytes  of  a message, including envelope
               information.
 
        <b><a href="postconf.5.html#smtpd_recipient_limit">smtpd_recipient_limit</a> (1000)</b>
-              The  maximal  number  of recipients that the Postfix SMTP server
+              The maximal number of recipients that the  Postfix  SMTP  server
               accepts per message delivery request.
 
        <b><a href="postconf.5.html#smtpd_timeout">smtpd_timeout</a> (normal: 300s, overload: 10s)</b>
-              The time limit for sending a Postfix SMTP  server  response  and
+              The  time  limit  for sending a Postfix SMTP server response and
               for receiving a remote SMTP client request.
 
        <b><a href="postconf.5.html#smtpd_history_flush_threshold">smtpd_history_flush_threshold</a> (100)</b>
-              The  maximal  number of lines in the Postfix SMTP server command
-              history before it is flushed upon receipt of EHLO, RSET, or  end
+              The maximal number of lines in the Postfix SMTP  server  command
+              history  before it is flushed upon receipt of EHLO, RSET, or end
               of DATA.
 
        Available in Postfix version 2.3 and later:
 
        <b><a href="postconf.5.html#smtpd_peername_lookup">smtpd_peername_lookup</a> (yes)</b>
-              Attempt  to  look up the remote SMTP client hostname, and verify
+              Attempt to look up the remote SMTP client hostname,  and  verify
               that the name matches the client IP address.
 
        The per SMTP client connection count and request rate limits are imple-
-       mented  in co-operation with the <a href="anvil.8.html"><b>anvil</b>(8)</a> service, and are available in
+       mented in co-operation with the <a href="anvil.8.html"><b>anvil</b>(8)</a> service, and are available  in
        Postfix version 2.2 and later.
 
        <b><a href="postconf.5.html#smtpd_client_connection_count_limit">smtpd_client_connection_count_limit</a> (50)</b>
-              How many simultaneous connections any client is allowed to  make
+              How  many simultaneous connections any client is allowed to make
               to this service.
 
        <b><a href="postconf.5.html#smtpd_client_connection_rate_limit">smtpd_client_connection_rate_limit</a> (0)</b>
-              The  maximal number of connection attempts any client is allowed
+              The maximal number of connection attempts any client is  allowed
               to make to this service per time unit.
 
        <b><a href="postconf.5.html#smtpd_client_message_rate_limit">smtpd_client_message_rate_limit</a> (0)</b>
-              The maximal number of message delivery requests that any  client
-              is  allowed to make to this service per time unit, regardless of
+              The  maximal number of message delivery requests that any client
+              is allowed to make to this service per time unit, regardless  of
               whether or not Postfix actually accepts those messages.
 
        <b><a href="postconf.5.html#smtpd_client_recipient_rate_limit">smtpd_client_recipient_rate_limit</a> (0)</b>
-              The maximal number of recipient addresses  that  any  client  is
-              allowed  to  send  to  this service per time unit, regardless of
+              The  maximal  number  of  recipient addresses that any client is
+              allowed to send to this service per  time  unit,  regardless  of
               whether or not Postfix actually accepts those recipients.
 
        <b><a href="postconf.5.html#smtpd_client_event_limit_exceptions">smtpd_client_event_limit_exceptions</a> ($<a href="postconf.5.html#mynetworks">mynetworks</a>)</b>
-              Clients that are excluded  from  smtpd_client_*_count/rate_limit
+              Clients  that  are excluded from smtpd_client_*_count/rate_limit
               restrictions.
 
        Available in Postfix version 2.3 and later:
 
        <b><a href="postconf.5.html#smtpd_client_new_tls_session_rate_limit">smtpd_client_new_tls_session_rate_limit</a> (0)</b>
-              The  maximal  number of new (i.e., uncached) TLS sessions that a
+              The maximal number of new (i.e., uncached) TLS sessions  that  a
               remote SMTP client is allowed to negotiate with this service per
               time unit.
 
@@ -899,74 +899,85 @@
 
        <b><a href="postconf.5.html#smtpd_per_record_deadline">smtpd_per_record_deadline</a> (normal: no, overload: yes)</b>
               Change  the  behavior  of  the  <a href="postconf.5.html#smtpd_timeout">smtpd_timeout</a>  and  <a href="postconf.5.html#smtpd_starttls_timeout">smtpd_start</a>-
-              <a href="postconf.5.html#smtpd_starttls_timeout">tls_timeout</a> time limits, from a time limit  per  read  or  write
-              system  call,  to  a  time  limit  to send or receive a complete
-              record (an SMTP command line, SMTP response line,  SMTP  message
+              <a href="postconf.5.html#smtpd_starttls_timeout">tls_timeout</a>  time  limits,  from  a time limit per read or write
+              system call, to a time limit  to  send  or  receive  a  complete
+              record  (an  SMTP command line, SMTP response line, SMTP message
               content line, or TLS protocol message).
 
        Available in Postfix version 3.1 and later:
 
        <b><a href="postconf.5.html#smtpd_client_auth_rate_limit">smtpd_client_auth_rate_limit</a> (0)</b>
-              The  maximal  number of AUTH commands that any client is allowed
-              to send to this service per time unit, regardless of whether  or
+              The maximal number of AUTH commands that any client  is  allowed
+              to  send to this service per time unit, regardless of whether or
               not Postfix actually accepts those commands.
 
        Available in Postfix 3.9, 3.8.1, 3.7.6, 3.6.10, 3.5.20 and later:
 
        <b><a href="postconf.5.html#smtpd_forbid_unauth_pipelining">smtpd_forbid_unauth_pipelining</a> (Postfix</b> &gt;<b>= 3.9: yes)</b>
-              Disconnect  remote  SMTP clients that violate <a href="https://tools.ietf.org/html/rfc2920">RFC 2920</a> (or 5321)
+              Disconnect remote SMTP clients that violate <a href="http://tools.ietf.org/html/rfc2920">RFC 2920</a>  (or  5321)
               command pipelining constraints.
 
+       Available in Postfix 3.9, 3.8.4, 3.7.9, 3.6.13, 3.5.23 and later:
+
+       <b><a href="postconf.5.html#smtpd_forbid_bare_newline">smtpd_forbid_bare_newline</a> (Postfix</b> &lt; <b>3.9: no)</b>
+              Reply  with  "Error:  bare  &lt;LF&gt; received" and disconnect when a
+              remote SMTP client sends a line ending in  &lt;LF&gt;,  violating  the
+              <a href="http://tools.ietf.org/html/rfc5321">RFC 5321</a> requirement that lines must end in &lt;CR&gt;&lt;LF&gt;.
+
+       <b><a href="postconf.5.html#smtpd_forbid_bare_newline_exclusions">smtpd_forbid_bare_newline_exclusions</a> ($<a href="postconf.5.html#mynetworks">mynetworks</a>)</b>
+              Exclude  the  specified  clients  from <a href="postconf.5.html#smtpd_forbid_bare_newline">smtpd_forbid_bare_newline</a>
+              enforcement.
+
 <b>TARPIT CONTROLS</b>
-       When  a  remote  SMTP  client makes errors, the Postfix SMTP server can
-       insert delays before responding. This can help to  slow  down  run-away
-       software.   The  behavior is controlled by an error counter that counts
+       When a remote SMTP client makes errors, the  Postfix  SMTP  server  can
+       insert  delays  before  responding. This can help to slow down run-away
+       software.  The behavior is controlled by an error counter  that  counts
        the number of errors within an SMTP session that a client makes without
        delivering mail.
 
        <b><a href="postconf.5.html#smtpd_error_sleep_time">smtpd_error_sleep_time</a> (1s)</b>
-              With  Postfix  version  2.1  and later: the SMTP server response
-              delay after a client has made more than  $<a href="postconf.5.html#smtpd_soft_error_limit">smtpd_soft_error_limit</a>
-              errors,  and  fewer than $<a href="postconf.5.html#smtpd_hard_error_limit">smtpd_hard_error_limit</a> errors, without
+              With Postfix version 2.1 and later:  the  SMTP  server  response
+              delay  after a client has made more than $<a href="postconf.5.html#smtpd_soft_error_limit">smtpd_soft_error_limit</a>
+              errors, and fewer than $<a href="postconf.5.html#smtpd_hard_error_limit">smtpd_hard_error_limit</a>  errors,  without
               delivering mail.
 
        <b><a href="postconf.5.html#smtpd_soft_error_limit">smtpd_soft_error_limit</a> (10)</b>
-              The number of errors a remote SMTP client  is  allowed  to  make
-              without  delivering  mail  before  the Postfix SMTP server slows
+              The  number  of  errors  a remote SMTP client is allowed to make
+              without delivering mail before the  Postfix  SMTP  server  slows
               down all its responses.
 
        <b><a href="postconf.5.html#smtpd_hard_error_limit">smtpd_hard_error_limit</a> (normal: 20, overload: 1)</b>
-              The maximal number of errors a remote SMTP client is allowed  to
+              The  maximal number of errors a remote SMTP client is allowed to
               make without delivering mail.
 
        <b><a href="postconf.5.html#smtpd_junk_command_limit">smtpd_junk_command_limit</a> (normal: 100, overload: 1)</b>
-              The  number  of  junk commands (NOOP, VRFY, ETRN or RSET) that a
-              remote SMTP client can  send  before  the  Postfix  SMTP  server
+              The number of junk commands (NOOP, VRFY, ETRN or  RSET)  that  a
+              remote  SMTP  client  can  send  before  the Postfix SMTP server
               starts to increment the error counter with each junk command.
 
        Available in Postfix version 2.1 and later:
 
        <b><a href="postconf.5.html#smtpd_recipient_overshoot_limit">smtpd_recipient_overshoot_limit</a> (1000)</b>
-              The  number  of recipients that a remote SMTP client can send in
+              The number of recipients that a remote SMTP client can  send  in
               excess  of  the  limit  specified  with  $<a href="postconf.5.html#smtpd_recipient_limit">smtpd_recipient_limit</a>,
-              before  the Postfix SMTP server increments the per-session error
+              before the Postfix SMTP server increments the per-session  error
               count for each excess recipient.
 
 <b>ACCESS POLICY DELEGATION CONTROLS</b>
-       As of version 2.1, Postfix can be configured to delegate access  policy
-       decisions  to  an  external  server that runs outside Postfix.  See the
+       As  of version 2.1, Postfix can be configured to delegate access policy
+       decisions to an external server that runs  outside  Postfix.   See  the
        file <a href="SMTPD_POLICY_README.html">SMTPD_POLICY_README</a> for more information.
 
        <b><a href="postconf.5.html#smtpd_policy_service_max_idle">smtpd_policy_service_max_idle</a> (300s)</b>
-              The time after which an idle SMTPD policy service connection  is
+              The  time after which an idle SMTPD policy service connection is
               closed.
 
        <b><a href="postconf.5.html#smtpd_policy_service_max_ttl">smtpd_policy_service_max_ttl</a> (1000s)</b>
-              The  time  after which an active SMTPD policy service connection
+              The time after which an active SMTPD policy  service  connection
               is closed.
 
        <b><a href="postconf.5.html#smtpd_policy_service_timeout">smtpd_policy_service_timeout</a> (100s)</b>
-              The time limit for connecting to, writing to, or receiving  from
+              The  time limit for connecting to, writing to, or receiving from
               a delegated SMTPD policy server.
 
        Available in Postfix version 3.0 and later:
@@ -976,81 +987,81 @@
               The default action when an SMTPD policy service request fails.
 
        <b><a href="postconf.5.html#smtpd_policy_service_request_limit">smtpd_policy_service_request_limit</a> (0)</b>
-              The  maximal number of requests per SMTPD policy service connec-
+              The maximal number of requests per SMTPD policy service  connec-
               tion, or zero (no limit).
 
        <b><a href="postconf.5.html#smtpd_policy_service_try_limit">smtpd_policy_service_try_limit</a> (2)</b>
-              The maximal number of attempts to send an SMTPD  policy  service
+              The  maximal  number of attempts to send an SMTPD policy service
               request before giving up.
 
        <b><a href="postconf.5.html#smtpd_policy_service_retry_delay">smtpd_policy_service_retry_delay</a> (1s)</b>
-              The  delay between attempts to resend a failed SMTPD policy ser-
+              The delay between attempts to resend a failed SMTPD policy  ser-
               vice request.
 
        Available in Postfix version 3.1 and later:
 
        <b><a href="postconf.5.html#smtpd_policy_service_policy_context">smtpd_policy_service_policy_context</a> (empty)</b>
-              Optional information that the Postfix SMTP server  specifies  in
-              the  "policy_context"  attribute  of  a  policy  service request
-              (originally, to share the same service endpoint  among  multiple
+              Optional  information  that the Postfix SMTP server specifies in
+              the "policy_context"  attribute  of  a  policy  service  request
+              (originally,  to  share the same service endpoint among multiple
               <a href="postconf.5.html#check_policy_service">check_policy_service</a> clients).
 
 <b>ACCESS CONTROLS</b>
-       The  <a href="SMTPD_ACCESS_README.html">SMTPD_ACCESS_README</a> document gives an introduction to all the SMTP
+       The <a href="SMTPD_ACCESS_README.html">SMTPD_ACCESS_README</a> document gives an introduction to all the  SMTP
        server access control features.
 
        <b><a href="postconf.5.html#smtpd_delay_reject">smtpd_delay_reject</a> (yes)</b>
-              Wait   until   the   RCPT   TO   command    before    evaluating
+              Wait    until    the   RCPT   TO   command   before   evaluating
               $<a href="postconf.5.html#smtpd_client_restrictions">smtpd_client_restrictions</a>,     $<a href="postconf.5.html#smtpd_helo_restrictions">smtpd_helo_restrictions</a>     and
               $<a href="postconf.5.html#smtpd_sender_restrictions">smtpd_sender_restrictions</a>,  or  wait  until  the  ETRN  command
-              before       evaluating      $<a href="postconf.5.html#smtpd_client_restrictions">smtpd_client_restrictions</a>      and
+              before      evaluating      $<a href="postconf.5.html#smtpd_client_restrictions">smtpd_client_restrictions</a>       and
               $<a href="postconf.5.html#smtpd_helo_restrictions">smtpd_helo_restrictions</a>.
 
        <b><a href="postconf.5.html#parent_domain_matches_subdomains">parent_domain_matches_subdomains</a> (see 'postconf -d' output)</b>
-              A list of Postfix features where the pattern "example.com"  also
-              matches  subdomains  of  example.com,  instead  of  requiring an
+              A  list of Postfix features where the pattern "example.com" also
+              matches subdomains  of  example.com,  instead  of  requiring  an
               explicit ".example.com" pattern.
 
        <b><a href="postconf.5.html#smtpd_client_restrictions">smtpd_client_restrictions</a> (empty)</b>
-              Optional restrictions that the Postfix SMTP  server  applies  in
+              Optional  restrictions  that  the Postfix SMTP server applies in
               the context of a client connection request.
 
        <b><a href="postconf.5.html#smtpd_helo_required">smtpd_helo_required</a> (no)</b>
-              Require  that  a  remote  SMTP client introduces itself with the
-              HELO or EHLO command before sending the MAIL  command  or  other
+              Require that a remote SMTP client  introduces  itself  with  the
+              HELO  or  EHLO  command before sending the MAIL command or other
               commands that require EHLO negotiation.
 
        <b><a href="postconf.5.html#smtpd_helo_restrictions">smtpd_helo_restrictions</a> (empty)</b>
-              Optional  restrictions  that  the Postfix SMTP server applies in
+              Optional restrictions that the Postfix SMTP  server  applies  in
               the context of a client HELO command.
 
        <b><a href="postconf.5.html#smtpd_sender_restrictions">smtpd_sender_restrictions</a> (empty)</b>
-              Optional restrictions that the Postfix SMTP  server  applies  in
+              Optional  restrictions  that  the Postfix SMTP server applies in
               the context of a client MAIL FROM command.
 
        <b><a href="postconf.5.html#smtpd_recipient_restrictions">smtpd_recipient_restrictions</a> (see 'postconf -d' output)</b>
-              Optional  restrictions  that  the Postfix SMTP server applies in
-              the   context   of   a   client   RCPT   TO    command,    after
+              Optional restrictions that the Postfix SMTP  server  applies  in
+              the    context    of   a   client   RCPT   TO   command,   after
               <a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a>.
 
        <b><a href="postconf.5.html#smtpd_etrn_restrictions">smtpd_etrn_restrictions</a> (empty)</b>
-              Optional  restrictions  that  the Postfix SMTP server applies in
+              Optional restrictions that the Postfix SMTP  server  applies  in
               the context of a client ETRN command.
 
        <b><a href="postconf.5.html#allow_untrusted_routing">allow_untrusted_routing</a> (no)</b>
-              Forward      mail      with       sender-specified       routing
-              (user[@%!]remote[@%!]site)  from  untrusted  clients to destina-
+              Forward       mail       with      sender-specified      routing
+              (user[@%!]remote[@%!]site) from untrusted  clients  to  destina-
               tions matching $<a href="postconf.5.html#relay_domains">relay_domains</a>.
 
        <b><a href="postconf.5.html#smtpd_restriction_classes">smtpd_restriction_classes</a> (empty)</b>
               User-defined aliases for groups of access restrictions.
 
        <b><a href="postconf.5.html#smtpd_null_access_lookup_key">smtpd_null_access_lookup_key</a> (</b>&lt;&gt;<b>)</b>
-              The lookup key to be used in SMTP <a href="access.5.html"><b>access</b>(5)</a>  tables  instead  of
+              The  lookup  key  to be used in SMTP <a href="access.5.html"><b>access</b>(5)</a> tables instead of
               the null sender address.
 
        <b><a href="postconf.5.html#permit_mx_backup_networks">permit_mx_backup_networks</a> (empty)</b>
-              Restrict  the use of the <a href="postconf.5.html#permit_mx_backup">permit_mx_backup</a> SMTP access feature to
+              Restrict the use of the <a href="postconf.5.html#permit_mx_backup">permit_mx_backup</a> SMTP access feature  to
               only domains whose primary MX hosts match the listed networks.
 
        Available in Postfix version 2.0 and later:
@@ -1060,19 +1071,19 @@
               applies in the context of the SMTP DATA command.
 
        <b><a href="postconf.5.html#smtpd_expansion_filter">smtpd_expansion_filter</a> (see 'postconf -d' output)</b>
-              What  characters  are  allowed  in $name expansions of RBL reply
+              What characters are allowed in $name  expansions  of  RBL  reply
               templates.
 
        Available in Postfix version 2.1 and later:
 
        <b><a href="postconf.5.html#smtpd_reject_unlisted_sender">smtpd_reject_unlisted_sender</a> (no)</b>
-              Request that the Postfix SMTP server rejects mail  from  unknown
-              sender  addresses,  even when no explicit <a href="postconf.5.html#reject_unlisted_sender">reject_unlisted_sender</a>
+              Request  that  the Postfix SMTP server rejects mail from unknown
+              sender addresses, even when no  explicit  <a href="postconf.5.html#reject_unlisted_sender">reject_unlisted_sender</a>
               access restriction is specified.
 
        <b><a href="postconf.5.html#smtpd_reject_unlisted_recipient">smtpd_reject_unlisted_recipient</a> (yes)</b>
-              Request that the Postfix SMTP server rejects  mail  for  unknown
-              recipient      addresses,      even     when     no     explicit
+              Request  that  the  Postfix SMTP server rejects mail for unknown
+              recipient     addresses,     even     when      no      explicit
               <a href="postconf.5.html#reject_unlisted_recipient">reject_unlisted_recipient</a> access restriction is specified.
 
        Available in Postfix version 2.2 and later:
@@ -1086,17 +1097,17 @@
        <b><a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a> (<a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>, <a href="postconf.5.html#permit_sasl_authenticated">permit_sasl_authenticated</a>,</b>
        <b><a href="postconf.5.html#defer_unauth_destination">defer_unauth_destination</a>)</b>
               Access restrictions for mail relay control that the Postfix SMTP
-              server applies in the context of the  RCPT  TO  command,  before
+              server  applies  in  the  context of the RCPT TO command, before
               <a href="postconf.5.html#smtpd_recipient_restrictions">smtpd_recipient_restrictions</a>.
 
 <b>SENDER AND RECIPIENT ADDRESS VERIFICATION CONTROLS</b>
-       Postfix  version  2.1 introduces sender and recipient address verifica-
+       Postfix version 2.1 introduces sender and recipient  address  verifica-
        tion.  This feature is implemented by sending probe email messages that
        are  not  actually  delivered.   This  feature  is  requested  via  the
-       <a href="postconf.5.html#reject_unverified_sender">reject_unverified_sender</a>   and    <a href="postconf.5.html#reject_unverified_recipient">reject_unverified_recipient</a>    access
-       restrictions.   The  status of verification probes is maintained by the
-       <a href="verify.8.html"><b>verify</b>(8)</a> server.  See the file <a href="ADDRESS_VERIFICATION_README.html">ADDRESS_VERIFICATION_README</a> for  infor-
-       mation  about how to configure and operate the Postfix sender/recipient
+       <a href="postconf.5.html#reject_unverified_sender">reject_unverified_sender</a>    and    <a href="postconf.5.html#reject_unverified_recipient">reject_unverified_recipient</a>   access
+       restrictions.  The status of verification probes is maintained  by  the
+       <a href="verify.8.html"><b>verify</b>(8)</a>  server.  See the file <a href="ADDRESS_VERIFICATION_README.html">ADDRESS_VERIFICATION_README</a> for infor-
+       mation about how to configure and operate the Postfix  sender/recipient
        address verification service.
 
        <b><a href="postconf.5.html#address_verify_poll_count">address_verify_poll_count</a> (normal: 3, overload: 1)</b>
@@ -1108,7 +1119,7 @@
               fication request in progress.
 
        <b><a href="postconf.5.html#address_verify_sender">address_verify_sender</a> ($<a href="postconf.5.html#double_bounce_sender">double_bounce_sender</a>)</b>
-              The sender address to use in address verification probes;  prior
+              The  sender address to use in address verification probes; prior
               to Postfix 2.5 the default was "postmaster".
 
        <b><a href="postconf.5.html#unverified_sender_reject_code">unverified_sender_reject_code</a> (450)</b>
@@ -1116,18 +1127,18 @@
               address is rejected by the <a href="postconf.5.html#reject_unverified_sender">reject_unverified_sender</a> restriction.
 
        <b><a href="postconf.5.html#unverified_recipient_reject_code">unverified_recipient_reject_code</a> (450)</b>
-              The  numerical  Postfix  SMTP  server  response when a recipient
-              address is rejected by the <a href="postconf.5.html#reject_unverified_recipient">reject_unverified_recipient</a>  restric-
+              The numerical Postfix SMTP  server  response  when  a  recipient
+              address  is rejected by the <a href="postconf.5.html#reject_unverified_recipient">reject_unverified_recipient</a> restric-
               tion.
 
        Available in Postfix version 2.6 and later:
 
        <b><a href="postconf.5.html#unverified_sender_defer_code">unverified_sender_defer_code</a> (450)</b>
-              The  numerical  Postfix  SMTP server response code when a sender
+              The numerical Postfix SMTP server response code  when  a  sender
               address probe fails due to a temporary error condition.
 
        <b><a href="postconf.5.html#unverified_recipient_defer_code">unverified_recipient_defer_code</a> (450)</b>
-              The numerical Postfix SMTP  server  response  when  a  recipient
+              The  numerical  Postfix  SMTP  server  response when a recipient
               address probe fails due to a temporary error condition.
 
        <b><a href="postconf.5.html#unverified_sender_reject_reason">unverified_sender_reject_reason</a> (empty)</b>
@@ -1139,17 +1150,17 @@
               <a href="postconf.5.html#reject_unverified_recipient">reject_unverified_recipient</a>.
 
        <b><a href="postconf.5.html#unverified_sender_tempfail_action">unverified_sender_tempfail_action</a> ($<a href="postconf.5.html#reject_tempfail_action">reject_tempfail_action</a>)</b>
-              The  Postfix  SMTP server's action when <a href="postconf.5.html#reject_unverified_sender">reject_unverified_sender</a>
+              The Postfix SMTP server's action  when  <a href="postconf.5.html#reject_unverified_sender">reject_unverified_sender</a>
               fails due to a temporary error condition.
 
        <b><a href="postconf.5.html#unverified_recipient_tempfail_action">unverified_recipient_tempfail_action</a> ($<a href="postconf.5.html#reject_tempfail_action">reject_tempfail_action</a>)</b>
-              The Postfix SMTP server's action when  <a href="postconf.5.html#reject_unverified_recipient">reject_unverified_recipi</a>-
+              The  Postfix SMTP server's action when <a href="postconf.5.html#reject_unverified_recipient">reject_unverified_recipi</a>-
               <a href="postconf.5.html#reject_unverified_recipient">ent</a> fails due to a temporary error condition.
 
        Available with Postfix 2.9 and later:
 
        <b><a href="postconf.5.html#address_verify_sender_ttl">address_verify_sender_ttl</a> (0s)</b>
-              The  time  between  changes  in  the  time-dependent  portion of
+              The time  between  changes  in  the  time-dependent  portion  of
               address verification probe sender addresses.
 
 <b>ACCESS CONTROL RESPONSES</b>
@@ -1161,36 +1172,36 @@
               map "reject" action.
 
        <b><a href="postconf.5.html#defer_code">defer_code</a> (450)</b>
-              The numerical Postfix SMTP server response code  when  a  remote
+              The  numerical  Postfix  SMTP server response code when a remote
               SMTP client request is rejected by the "defer" restriction.
 
        <b><a href="postconf.5.html#invalid_hostname_reject_code">invalid_hostname_reject_code</a> (501)</b>
-              The  numerical Postfix SMTP server response code when the client
-              HELO  or   EHLO   command   parameter   is   rejected   by   the
+              The numerical Postfix SMTP server response code when the  client
+              HELO   or   EHLO   command   parameter   is   rejected   by  the
               <a href="postconf.5.html#reject_invalid_helo_hostname">reject_invalid_helo_hostname</a> restriction.
 
        <b><a href="postconf.5.html#maps_rbl_reject_code">maps_rbl_reject_code</a> (554)</b>
-              The  numerical  Postfix  SMTP server response code when a remote
-              SMTP  client  request  is  blocked  by  the   <a href="postconf.5.html#reject_rbl_client">reject_rbl_client</a>,
+              The numerical Postfix SMTP server response code  when  a  remote
+              SMTP   client  request  is  blocked  by  the  <a href="postconf.5.html#reject_rbl_client">reject_rbl_client</a>,
               <a href="postconf.5.html#reject_rhsbl_client">reject_rhsbl_client</a>,                <a href="postconf.5.html#reject_rhsbl_reverse_client">reject_rhsbl_reverse_client</a>,
               <a href="postconf.5.html#reject_rhsbl_sender">reject_rhsbl_sender</a> or <a href="postconf.5.html#reject_rhsbl_recipient">reject_rhsbl_recipient</a> restriction.
 
        <b><a href="postconf.5.html#non_fqdn_reject_code">non_fqdn_reject_code</a> (504)</b>
-              The numerical Postfix SMTP  server  reply  code  when  a  client
-              request   is   rejected  by  the  <a href="postconf.5.html#reject_non_fqdn_helo_hostname">reject_non_fqdn_helo_hostname</a>,
+              The  numerical  Postfix  SMTP  server  reply  code when a client
+              request  is  rejected  by   the   <a href="postconf.5.html#reject_non_fqdn_helo_hostname">reject_non_fqdn_helo_hostname</a>,
               <a href="postconf.5.html#reject_non_fqdn_sender">reject_non_fqdn_sender</a> or <a href="postconf.5.html#reject_non_fqdn_recipient">reject_non_fqdn_recipient</a> restriction.
 
        <b><a href="postconf.5.html#plaintext_reject_code">plaintext_reject_code</a> (450)</b>
-              The  numerical  Postfix SMTP server response code when a request
+              The numerical Postfix SMTP server response code when  a  request
               is rejected by the <b><a href="postconf.5.html#reject_plaintext_session">reject_plaintext_session</a></b> restriction.
 
        <b><a href="postconf.5.html#reject_code">reject_code</a> (554)</b>
-              The numerical Postfix SMTP server response code  when  a  remote
+              The  numerical  Postfix  SMTP server response code when a remote
               SMTP client request is rejected by the "reject" restriction.
 
        <b><a href="postconf.5.html#relay_domains_reject_code">relay_domains_reject_code</a> (554)</b>
-              The  numerical  Postfix  SMTP server response code when a client
-              request is rejected by the  <a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a>  recipient
+              The numerical Postfix SMTP server response code  when  a  client
+              request  is  rejected by the <a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a> recipient
               restriction.
 
        <b><a href="postconf.5.html#unknown_address_reject_code">unknown_address_reject_code</a> (450)</b>
@@ -1198,24 +1209,24 @@
               a sender or recipient address because its domain is unknown.
 
        <b><a href="postconf.5.html#unknown_client_reject_code">unknown_client_reject_code</a> (450)</b>
-              The numerical Postfix SMTP server response code  when  a  client
-              without  valid  address  &lt;=&gt;  name  mapping  is  rejected by the
+              The  numerical  Postfix  SMTP server response code when a client
+              without valid address  &lt;=&gt;  name  mapping  is  rejected  by  the
               <a href="postconf.5.html#reject_unknown_client_hostname">reject_unknown_client_hostname</a> restriction.
 
        <b><a href="postconf.5.html#unknown_hostname_reject_code">unknown_hostname_reject_code</a> (450)</b>
-              The numerical Postfix SMTP server response code when  the  host-
-              name  specified with the HELO or EHLO command is rejected by the
+              The  numerical  Postfix SMTP server response code when the host-
+              name specified with the HELO or EHLO command is rejected by  the
               <a href="postconf.5.html#reject_unknown_helo_hostname">reject_unknown_helo_hostname</a> restriction.
 
        Available in Postfix version 2.0 and later:
 
        <b><a href="postconf.5.html#default_rbl_reply">default_rbl_reply</a> (see 'postconf -d' output)</b>
-              The default Postfix SMTP server response template for a  request
+              The  default Postfix SMTP server response template for a request
               that is rejected by an RBL-based restriction.
 
        <b><a href="postconf.5.html#multi_recipient_bounce_reject_code">multi_recipient_bounce_reject_code</a> (550)</b>
-              The  numerical  Postfix  SMTP server response code when a remote
-              SMTP client  request  is  blocked  by  the  <a href="postconf.5.html#reject_multi_recipient_bounce">reject_multi_recipi</a>-
+              The numerical Postfix SMTP server response code  when  a  remote
+              SMTP  client  request  is  blocked  by  the <a href="postconf.5.html#reject_multi_recipient_bounce">reject_multi_recipi</a>-
               <a href="postconf.5.html#reject_multi_recipient_bounce">ent_bounce</a> restriction.
 
        <b><a href="postconf.5.html#rbl_reply_maps">rbl_reply_maps</a> (empty)</b>
@@ -1225,52 +1236,52 @@
 
        <b><a href="postconf.5.html#access_map_defer_code">access_map_defer_code</a> (450)</b>
               The numerical Postfix SMTP server response code for an <a href="access.5.html"><b>access</b>(5)</a>
-              map   "defer"    action,    including    "<a href="postconf.5.html#defer_if_permit">defer_if_permit</a>"    or
+              map    "defer"    action,    including    "<a href="postconf.5.html#defer_if_permit">defer_if_permit</a>"   or
               "<a href="postconf.5.html#defer_if_reject">defer_if_reject</a>".
 
        <b><a href="postconf.5.html#reject_tempfail_action">reject_tempfail_action</a> (<a href="postconf.5.html#defer_if_permit">defer_if_permit</a>)</b>
-              The  Postfix SMTP server's action when a reject-type restriction
+              The Postfix SMTP server's action when a reject-type  restriction
               fails due to a temporary error condition.
 
        <b><a href="postconf.5.html#unknown_helo_hostname_tempfail_action">unknown_helo_hostname_tempfail_action</a> ($<a href="postconf.5.html#reject_tempfail_action">reject_tempfail_action</a>)</b>
-              The Postfix SMTP server's action when  <a href="postconf.5.html#reject_unknown_helo_hostname">reject_unknown_helo_host</a>-
+              The  Postfix SMTP server's action when <a href="postconf.5.html#reject_unknown_helo_hostname">reject_unknown_helo_host</a>-
               <a href="postconf.5.html#reject_unknown_helo_hostname">name</a> fails due to a temporary error condition.
 
        <b><a href="postconf.5.html#unknown_address_tempfail_action">unknown_address_tempfail_action</a> ($<a href="postconf.5.html#reject_tempfail_action">reject_tempfail_action</a>)</b>
-              The       Postfix       SMTP      server's      action      when
-              <a href="postconf.5.html#reject_unknown_sender_domain">reject_unknown_sender_domain</a> or  <a href="postconf.5.html#reject_unknown_recipient_domain">reject_unknown_recipient_domain</a>
+              The      Postfix      SMTP      server's       action       when
+              <a href="postconf.5.html#reject_unknown_sender_domain">reject_unknown_sender_domain</a>  or <a href="postconf.5.html#reject_unknown_recipient_domain">reject_unknown_recipient_domain</a>
               fail due to a temporary error condition.
 
 <b>MISCELLANEOUS CONTROLS</b>
        <b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b>
-              The  default  location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con-
+              The default location of the Postfix <a href="postconf.5.html">main.cf</a> and  <a href="master.5.html">master.cf</a>  con-
               figuration files.
 
        <b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b>
-              How much time a Postfix daemon process  may  take  to  handle  a
+              How  much  time  a  Postfix  daemon process may take to handle a
               request before it is terminated by a built-in watchdog timer.
 
        <b><a href="postconf.5.html#command_directory">command_directory</a> (see 'postconf -d' output)</b>
               The location of all postfix administrative commands.
 
        <b><a href="postconf.5.html#double_bounce_sender">double_bounce_sender</a> (double-bounce)</b>
-              The  sender  address of postmaster notifications that are gener-
+              The sender address of postmaster notifications that  are  gener-
               ated by the mail system.
 
        <b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b>
-              The time limit for sending  or  receiving  information  over  an
+              The  time  limit  for  sending  or receiving information over an
               internal communication channel.
 
        <b><a href="postconf.5.html#mail_name">mail_name</a> (Postfix)</b>
-              The  mail system name that is displayed in Received: headers, in
+              The mail system name that is displayed in Received: headers,  in
               the SMTP greeting banner, and in bounced mail.
 
        <b><a href="postconf.5.html#mail_owner">mail_owner</a> (postfix)</b>
-              The UNIX system account that owns the  Postfix  queue  and  most
+              The  UNIX  system  account  that owns the Postfix queue and most
               Postfix daemon processes.
 
        <b><a href="postconf.5.html#max_idle">max_idle</a> (100s)</b>
-              The  maximum  amount of time that an idle Postfix daemon process
+              The maximum amount of time that an idle Postfix  daemon  process
               waits for an incoming connection before terminating voluntarily.
 
        <b><a href="postconf.5.html#max_use">max_use</a> (100)</b>
@@ -1281,11 +1292,11 @@
               The internet hostname of this mail system.
 
        <b><a href="postconf.5.html#mynetworks">mynetworks</a> (see 'postconf -d' output)</b>
-              The list of "trusted" remote SMTP clients that have more  privi-
+              The  list of "trusted" remote SMTP clients that have more privi-
               leges than "strangers".
 
        <b><a href="postconf.5.html#myorigin">myorigin</a> ($<a href="postconf.5.html#myhostname">myhostname</a>)</b>
-              The  domain  name that locally-posted mail appears to come from,
+              The domain name that locally-posted mail appears to  come  from,
               and that locally posted mail is delivered to.
 
        <b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b>
@@ -1298,25 +1309,25 @@
               The location of the Postfix top-level queue directory.
 
        <b><a href="postconf.5.html#recipient_delimiter">recipient_delimiter</a> (empty)</b>
-              The set of characters that can separate a  user  name  from  its
-              extension  (example: user+foo), or a .forward file name from its
+              The  set  of  characters  that can separate a user name from its
+              extension (example: user+foo), or a .forward file name from  its
               extension (example: .forward+foo).
 
        <b><a href="postconf.5.html#smtpd_banner">smtpd_banner</a> ($<a href="postconf.5.html#myhostname">myhostname</a> ESMTP $<a href="postconf.5.html#mail_name">mail_name</a>)</b>
-              The text that follows the 220 status code in the  SMTP  greeting
+              The  text  that follows the 220 status code in the SMTP greeting
               banner.
 
        <b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b>
               The syslog facility of Postfix logging.
 
        <b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b>
-              A  prefix  that  is  prepended  to  the  process  name in syslog
+              A prefix that  is  prepended  to  the  process  name  in  syslog
               records, so that, for example, "smtpd" becomes "prefix/smtpd".
 
        Available in Postfix version 2.2 and later:
 
        <b><a href="postconf.5.html#smtpd_forbidden_commands">smtpd_forbidden_commands</a> (CONNECT, GET, POST)</b>
-              List of commands that cause the Postfix SMTP server  to  immedi-
+              List  of  commands that cause the Postfix SMTP server to immedi-
               ately terminate the session with a 221 code.
 
        Available in Postfix version 2.5 and later:
@@ -1333,7 +1344,7 @@
        Available in Postfix 3.4 and later:
 
        <b><a href="postconf.5.html#smtpd_reject_footer_maps">smtpd_reject_footer_maps</a> (empty)</b>
-              Lookup tables, indexed by the complete Postfix SMTP  server  4xx
+              Lookup  tables,  indexed by the complete Postfix SMTP server 4xx
               or 5xx response, with reject footer templates.
 
 <b>SEE ALSO</b>
diff -ur --new-file /var/tmp/postfix-3.5.22/man/man5/postconf.5 ./man/man5/postconf.5
--- /var/tmp/postfix-3.5.22/man/man5/postconf.5	2023-11-01 12:43:47.000000000 -0400
+++ ./man/man5/postconf.5	2023-12-22 13:58:15.000000000 -0500
@@ -10206,6 +10206,61 @@
 parameter $name expansion.
 .PP
 This feature is available in Postfix 2.0 and later.
+.SH smtpd_forbid_bare_newline (default: Postfix < 3.9: no)
+Reply with "Error: bare <LF> received" and disconnect
+when a remote SMTP client sends a line ending in <LF>, violating
+the RFC 5321 requirement that lines must end in <CR><LF>.
+This feature is disbled by default with Postfix < 3.9. Use
+smtpd_forbid_bare_newline_exclusions to exclude non\-standard clients
+such as netcat. Specify "smtpd_forbid_bare_newline = no" to disable
+(not recommended for an Internet\-connected MTA).
+.PP
+See
+https://www.postfix.org/smtp\-smuggling.html for details.
+.PP
+Example:
+.sp
+.in +4
+.nf
+.na
+.ft C
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non\-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+smtpd_forbid_bare_newline = yes
+smtpd_forbid_bare_newline_exclusions = $mynetworks
+.fi
+.ad
+.ft R
+.in -4
+.PP
+This feature is available in Postfix >= 3.9, 3.8.4, 3.7.9,
+3.6.13, and 3.5.23.
+.SH smtpd_forbid_bare_newline_exclusions (default: $mynetworks)
+Exclude the specified clients from smtpd_forbid_bare_newline
+enforcement. It uses the same syntax and parent\-domain matching
+behavior as mynetworks.
+.PP
+Example:
+.sp
+.in +4
+.nf
+.na
+.ft C
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non\-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+smtpd_forbid_bare_newline = yes
+smtpd_forbid_bare_newline_exclusions = $mynetworks
+.fi
+.ad
+.ft R
+.in -4
+.PP
+This feature is available in Postfix >= 3.9, 3.8.4, 3.7.9,
+3.6.13, and 3.5.23.
 .SH smtpd_forbid_unauth_pipelining (default: Postfix >= 3.9: yes)
 Disconnect remote SMTP clients that violate RFC 2920 (or 5321)
 command pipelining constraints. The server replies with "554 5.5.0
diff -ur --new-file /var/tmp/postfix-3.5.22/man/man8/smtpd.8 ./man/man8/smtpd.8
--- /var/tmp/postfix-3.5.22/man/man8/smtpd.8	2023-11-01 12:43:29.000000000 -0400
+++ ./man/man8/smtpd.8	2023-12-22 13:58:15.000000000 -0500
@@ -809,6 +809,15 @@
 .IP "\fBsmtpd_forbid_unauth_pipelining (Postfix >= 3.9: yes)\fR"
 Disconnect remote SMTP clients that violate RFC 2920 (or 5321)
 command pipelining constraints.
+.PP
+Available in Postfix 3.9, 3.8.4, 3.7.9, 3.6.13, 3.5.23 and later:
+.IP "\fBsmtpd_forbid_bare_newline (Postfix < 3.9: no)\fR"
+Reply with "Error: bare <LF> received" and disconnect
+when a remote SMTP client sends a line ending in <LF>, violating
+the RFC 5321 requirement that lines must end in <CR><LF>.
+.IP "\fBsmtpd_forbid_bare_newline_exclusions ($mynetworks)\fR"
+Exclude the specified clients from smtpd_forbid_bare_newline
+enforcement.
 .SH "TARPIT CONTROLS"
 .na
 .nf
diff -ur --new-file /var/tmp/postfix-3.5.22/mantools/postlink ./mantools/postlink
--- /var/tmp/postfix-3.5.22/mantools/postlink	2023-06-05 16:34:00.000000000 -0400
+++ ./mantools/postlink	2023-12-22 13:55:36.000000000 -0500
@@ -548,6 +548,8 @@
     s;\bsmtpd_etrn_restrictions\b;<a href="postconf.5.html#smtpd_etrn_restrictions">$&</a>;g;
     s;\bsmtpd_expansion_filter\b;<a href="postconf.5.html#smtpd_expansion_filter">$&</a>;g;
     s;\bsmtpd_for[-</bB>]*\n*[ <bB>]*bidden_commands\b;<a href="postconf.5.html#smtpd_forbidden_commands">$&</a>;g;
+    s;\bsmtpd_for[-</bB>]*\n*[ <bB>]*bid_bare_newline\b;<a href="postconf.5.html#smtpd_forbid_bare_newline">$&</a>;g;
+    s;\bsmtpd_for[-</bB>]*\n*[ <bB>]*bid_bare_newline_exclusions\b;<a href="postconf.5.html#smtpd_forbid_bare_newline_exclusions">$&</a>;g;
     s;\bsmtpd_for[-</bB>]*\n*[ <bB>]*bid_unauth_pipelining\b;<a href="postconf.5.html#smtpd_forbid_unauth_pipelining">$&</a>;g;
     s;\bsmtpd_hard_error_limit\b;<a href="postconf.5.html#smtpd_hard_error_limit">$&</a>;g;
     s;\bsmtpd_helo_required\b;<a href="postconf.5.html#smtpd_helo_required">$&</a>;g;
diff -ur --new-file /var/tmp/postfix-3.5.22/proto/postconf.proto ./proto/postconf.proto
--- /var/tmp/postfix-3.5.22/proto/postconf.proto	2023-10-31 19:40:13.000000000 -0400
+++ ./proto/postconf.proto	2023-12-22 13:55:36.000000000 -0500
@@ -17863,6 +17863,57 @@
 <p> This feature is available in Postfix &ge; 3.9, 3.8.1, 3.7.6,
 3.6.10, and 3.5.20. </p>
 
+%PARAM smtpd_forbid_bare_newline Postfix &lt; 3.9: no
+
+<p> Reply with "Error: bare &lt;LF&gt; received" and disconnect
+when a remote SMTP client sends a line ending in &lt;LF&gt;, violating
+the RFC 5321 requirement that lines must end in &lt;CR&gt;&lt;LF&gt;.
+This feature is disbled by default with Postfix &lt; 3.9. Use
+smtpd_forbid_bare_newline_exclusions to exclude non-standard clients
+such as netcat. Specify "smtpd_forbid_bare_newline = no" to disable
+(not recommended for an Internet-connected MTA). </p>
+
+<p> See <a href="https://www.postfix.org/smtp-smuggling.html">
+https://www.postfix.org/smtp-smuggling.html</a> for details.
+
+<p> Example: </p>
+
+<blockquote>
+<pre>
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+smtpd_forbid_bare_newline = yes
+smtpd_forbid_bare_newline_exclusions = $mynetworks
+</pre>
+</blockquote>
+
+<p> This feature is available in Postfix &ge; 3.9, 3.8.4, 3.7.9,
+3.6.13, and 3.5.23. </p>
+
+%PARAM smtpd_forbid_bare_newline_exclusions $mynetworks
+
+<p> Exclude the specified clients from smtpd_forbid_bare_newline
+enforcement. It uses the same syntax and parent-domain matching 
+behavior as mynetworks. </p>
+
+<p> Example: </p>
+
+<blockquote>
+<pre>
+# Disconnect remote SMTP clients that send bare newlines, but allow
+# local clients with non-standard SMTP implementations such as netcat,
+# fax machines, or load balancer health checks.
+#
+smtpd_forbid_bare_newline = yes
+smtpd_forbid_bare_newline_exclusions = $mynetworks
+</pre>
+</blockquote>
+
+<p> This feature is available in Postfix &ge; 3.9, 3.8.4, 3.7.9,
+3.6.13, and 3.5.23. </p>
+
 %PARAM smtpd_forbid_unauth_pipelining Postfix &ge; 3.9: yes
 
 <p> Disconnect remote SMTP clients that violate RFC 2920 (or 5321)
diff -ur --new-file /var/tmp/postfix-3.5.22/src/global/mail_params.h ./src/global/mail_params.h
--- /var/tmp/postfix-3.5.22/src/global/mail_params.h	2023-06-05 17:44:55.000000000 -0400
+++ ./src/global/mail_params.h	2023-12-22 13:55:36.000000000 -0500
@@ -4142,7 +4142,16 @@
 extern char *var_smtpd_dns_re_filter;
 
  /*
-  * Share TLS sessions through tlproxy(8).
+  * Backwards compatibility.
+  */
+#define VAR_SMTPD_FORBID_BARE_LF	"smtpd_forbid_bare_newline"
+#define DEF_SMTPD_FORBID_BARE_LF	0
+
+#define VAR_SMTPD_FORBID_BARE_LF_EXCL	"smtpd_forbid_bare_newline_exclusions"
+#define DEF_SMTPD_FORBID_BARE_LF_EXCL	"$" VAR_MYNETWORKS
+
+ /*
+  * Share TLS sessions through tlsproxy(8).
   */
 #define VAR_SMTP_TLS_CONN_REUSE		"smtp_tls_connection_reuse"
 #define DEF_SMTP_TLS_CONN_REUSE		0
diff -ur --new-file /var/tmp/postfix-3.5.22/src/global/smtp_stream.c ./src/global/smtp_stream.c
--- /var/tmp/postfix-3.5.22/src/global/smtp_stream.c	2018-11-30 18:41:11.000000000 -0500
+++ ./src/global/smtp_stream.c	2023-12-22 13:55:36.000000000 -0500
@@ -50,6 +50,8 @@
 /*	VSTREAM *stream;
 /*	char	*format;
 /*	va_list	ap;
+/*
+/*	int	smtp_forbid_bare_lf;
 /* AUXILIARY API
 /*	int	smtp_get_noexcept(vp, stream, maxlen, flags)
 /*	VSTRING	*vp;
@@ -124,11 +126,16 @@
 /*	smtp_vprintf() is the machine underneath smtp_printf().
 /*
 /*	smtp_get_noexcept() implements the subset of smtp_get()
-/*	without timeouts and without making long jumps. Instead,
+/*	without long jumps for timeout or EOF errors. Instead,
 /*	query the stream status with vstream_feof() etc.
+/*	This function will make a VSTREAM long jump (error code
+/*	SMTP_ERR_LF) when rejecting input with a bare newline byte.
 /*
 /*	smtp_timeout_setup() is a backwards-compatibility interface
 /*	for programs that don't require per-record deadline support.
+/*
+/*	smtp_forbid_bare_lf controls whether smtp_get_noexcept()
+/*	will reject input with a bare newline byte.
 /* DIAGNOSTICS
 /* .fi
 /* .ad
@@ -201,6 +208,8 @@
 
 #include "smtp_stream.h"
 
+int     smtp_forbid_bare_lf;
+
 /* smtp_timeout_reset - reset per-stream error flags, restart deadline timer */
 
 static void smtp_timeout_reset(VSTREAM *stream)
@@ -404,6 +413,9 @@
 	 */
     case '\n':
 	vstring_truncate(vp, VSTRING_LEN(vp) - 1);
+	if (smtp_forbid_bare_lf
+	    && (VSTRING_LEN(vp) == 0 || vstring_end(vp)[-1] != '\r'))
+	    vstream_longjmp(stream, SMTP_ERR_LF);
 	while (VSTRING_LEN(vp) > 0 && vstring_end(vp)[-1] == '\r')
 	    vstring_truncate(vp, VSTRING_LEN(vp) - 1);
 	VSTRING_TERMINATE(vp);
diff -ur --new-file /var/tmp/postfix-3.5.22/src/global/smtp_stream.h ./src/global/smtp_stream.h
--- /var/tmp/postfix-3.5.22/src/global/smtp_stream.h	2018-11-27 18:38:32.000000000 -0500
+++ ./src/global/smtp_stream.h	2023-12-22 13:55:36.000000000 -0500
@@ -32,6 +32,7 @@
 #define SMTP_ERR_QUIET	3		/* silent cleanup (application) */
 #define SMTP_ERR_NONE	4		/* non-error case */
 #define SMTP_ERR_DATA	5		/* application data error */
+#define SMTP_ERR_LF	6		/* bare <LF> protocol error */
 
 extern void smtp_stream_setup(VSTREAM *, int, int);
 extern void PRINTFLIKE(2, 3) smtp_printf(VSTREAM *, const char *,...);
@@ -43,6 +44,7 @@
 extern void smtp_fwrite(const char *, ssize_t len, VSTREAM *);
 extern void smtp_fread_buf(VSTRING *, ssize_t len, VSTREAM *);
 extern void smtp_fputc(int, VSTREAM *);
+extern int smtp_forbid_bare_lf;
 
 extern void smtp_vprintf(VSTREAM *, const char *, va_list);
 
diff -ur --new-file /var/tmp/postfix-3.5.22/src/smtpd/smtpd.c ./src/smtpd/smtpd.c
--- /var/tmp/postfix-3.5.22/src/smtpd/smtpd.c	2023-10-26 18:37:13.000000000 -0400
+++ ./src/smtpd/smtpd.c	2023-12-22 13:55:36.000000000 -0500
@@ -763,6 +763,15 @@
 /* .IP "\fBsmtpd_forbid_unauth_pipelining (Postfix >= 3.9: yes)\fR"
 /*	Disconnect remote SMTP clients that violate RFC 2920 (or 5321)
 /*	command pipelining constraints.
+/* .PP
+/*	Available in Postfix 3.9, 3.8.4, 3.7.9, 3.6.13, 3.5.23 and later:
+/* .IP "\fBsmtpd_forbid_bare_newline (Postfix < 3.9: no)\fR"
+/*	Reply with "Error: bare <LF> received" and disconnect
+/*	when a remote SMTP client sends a line ending in <LF>, violating
+/*	the RFC 5321 requirement that lines must end in <CR><LF>.
+/* .IP "\fBsmtpd_forbid_bare_newline_exclusions ($mynetworks)\fR"
+/*	Exclude the specified clients from smtpd_forbid_bare_newline
+/*	enforcement.
 /* TARPIT CONTROLS
 /* .ad
 /* .fi
@@ -1468,6 +1477,10 @@
 char   *var_smtpd_uproxy_proto;
 int     var_smtpd_uproxy_tmout;
 
+bool    var_smtpd_forbid_bare_lf;
+char   *var_smtpd_forbid_bare_lf_excl;
+static NAMADR_LIST *bare_lf_excl;
+
  /*
   * Silly little macros.
   */
@@ -1542,6 +1555,7 @@
 #define REASON_TIMEOUT		"timeout"
 #define REASON_LOST_CONNECTION	"lost connection"
 #define REASON_ERROR_LIMIT	"too many errors"
+#define REASON_BARE_LF		"bare <LF> received"
 
 #ifdef USE_TLS
 
@@ -3968,6 +3982,7 @@
      */
     done = 0;
     do {
+	int     payload_err;
 
 	/*
 	 * Do not skip the smtp_fread_buf() call if read_len == 0. We still
@@ -3981,6 +3996,10 @@
 	smtp_fread_buf(state->buffer, read_len, state->client);
 	state->bdat_get_stream = vstream_memreopen(
 			   state->bdat_get_stream, state->buffer, O_RDONLY);
+	vstream_control(state->bdat_get_stream, CA_VSTREAM_CTL_EXCEPT,
+			CA_VSTREAM_CTL_END);
+	if ((payload_err = vstream_setjmp(state->bdat_get_stream)) != 0)
+	    vstream_longjmp(state->client, payload_err);
 
 	/*
 	 * Read lines from the fragment. The last line may continue in the
@@ -4656,6 +4675,9 @@
      */
     xclient_allowed =
 	namadr_list_match(xclient_hosts, state->name, state->addr);
+    smtp_forbid_bare_lf = SMTPD_STAND_ALONE((state)) == 0
+	&& var_smtpd_forbid_bare_lf
+	&& !namadr_list_match(bare_lf_excl, state->name, state->addr);
     /* NOT: tls_reset() */
     if (got_helo == 0)
 	helo_reset(state);
@@ -5474,6 +5496,13 @@
 			     var_myhostname);
 	break;
 
+    case SMTP_ERR_LF:
+	state->reason = REASON_BARE_LF;
+	if (vstream_setjmp(state->client) == 0)
+	    smtpd_chat_reply(state, "521 5.5.2 %s Error: bare <LF> received",
+			     var_myhostname);
+	break;
+
     case 0:
 
 	/*
@@ -6033,6 +6062,13 @@
 	namadr_list_match(xforward_hosts, state.name, state.addr);
 
     /*
+     * Enforce strict SMTP line endings, with compatibility exclusions.
+     */
+    smtp_forbid_bare_lf = SMTPD_STAND_ALONE((&state)) == 0
+	&& var_smtpd_forbid_bare_lf
+	&& !namadr_list_match(bare_lf_excl, state.name, state.addr);
+
+    /*
      * See if we need to turn on verbose logging for this client.
      */
     debug_peer_check(state.name, state.addr);
@@ -6093,6 +6129,10 @@
     hogger_list = namadr_list_init(VAR_SMTPD_HOGGERS, MATCH_FLAG_RETURN
 				   | match_parent_style(VAR_SMTPD_HOGGERS),
 				   var_smtpd_hoggers);
+    bare_lf_excl = namadr_list_init(VAR_SMTPD_FORBID_BARE_LF_EXCL,
+				    MATCH_FLAG_RETURN
+				    | match_parent_style(VAR_MYNETWORKS),
+				    var_smtpd_forbid_bare_lf_excl);
 
     /*
      * Open maps before dropping privileges so we can read passwords etc.
@@ -6451,6 +6491,7 @@
 	VAR_SMTPD_DELAY_OPEN, DEF_SMTPD_DELAY_OPEN, &var_smtpd_delay_open,
 	VAR_SMTPD_CLIENT_PORT_LOG, DEF_SMTPD_CLIENT_PORT_LOG, &var_smtpd_client_port_log,
 	VAR_SMTPD_FORBID_UNAUTH_PIPE, DEF_SMTPD_FORBID_UNAUTH_PIPE, &var_smtpd_forbid_unauth_pipe,
+	VAR_SMTPD_FORBID_BARE_LF, DEF_SMTPD_FORBID_BARE_LF, &var_smtpd_forbid_bare_lf,
 	0,
     };
     static const CONFIG_NBOOL_TABLE nbool_table[] = {
@@ -6564,6 +6605,7 @@
 	VAR_SMTPD_POLICY_CONTEXT, DEF_SMTPD_POLICY_CONTEXT, &var_smtpd_policy_context, 0, 0,
 	VAR_SMTPD_DNS_RE_FILTER, DEF_SMTPD_DNS_RE_FILTER, &var_smtpd_dns_re_filter, 0, 0,
 	VAR_SMTPD_REJ_FTR_MAPS, DEF_SMTPD_REJ_FTR_MAPS, &var_smtpd_rej_ftr_maps, 0, 0,
+	VAR_SMTPD_FORBID_BARE_LF_EXCL, DEF_SMTPD_FORBID_BARE_LF_EXCL, &var_smtpd_forbid_bare_lf_excl, 0, 0,
 	0,
     };
     static const CONFIG_RAW_TABLE raw_table[] = {