diff --git a/README_FILES/README_UNICODE b/README_FILES/README_UNICODE
new file mode 100644
index 0000000..77d8d1a
--- /dev/null
+++ b/README_FILES/README_UNICODE
@@ -0,0 +1,31 @@
+Unicode email addresses
+
+RFCs 6530-3 add support for unicode email addresses; this version of
+Postfix supports that. The support was paid for by cnnic.cn and the
+code written by an RFC contributor.
+
+The overall design is one of allowing UTF-8 in the message and in MAIL
+FROM/RCPT TO commands. The changes are subtle enough that procmail
+didn't need any changes to work with unicode addresses, even though
+most of the code is over 20 years old.
+
+The xn-- domains you may have seen are not visible in SMTP or email
+messages.  Postfix converts blåbærsyltetøy to xn--blbrsyltety-y8ao3x
+while doing the MX lookup.
+
+Postfix supports unicode addresses if it's built with ICU (which is
+autodetected at build time), and advertises that using the SMTPUTF8
+extension.  Postfix will use unicode while talking to another server
+only if the message or addressses needs it. If it's possible to use
+classic SMTP, Postfix does that.
+
+The variable myhostname should be a plain ASCII hostname. Even if you
+intend to send only unicode mail, Postfix needs to use the name in the
+SMTP EHLO command, and that command does not accept UTF-8. And if you
+intend to send ASCII mail, you certainly need an ASCII hostname.
+
+The variables myorigin and mydestinations can contain UTF-8, as can
+localparts.
+
+You can test that Postfix' unicode support works by sending mail to
+the autoresponder jøran@blåbærsyltetøy.gulbrandsen.priv.no.
diff --git a/makedefs b/makedefs
index 5f3bcc7..e8bf924 100644
--- a/makedefs
+++ b/makedefs
@@ -576,6 +576,44 @@ EOF
 		   rm -f makedefs.test makedefs.test.[co]
 esac
 
+
+#
+# Look for ICU and enable unicode email if available. This tests
+# a different function that Postfix uses in order to avoid having UTF8
+# in this file. The two functions use the same data structures, so they
+# should be equivalent for testing purposes.
+#
+case "$CCARGS" in
+ *-DNO_EAI*) ;;
+	  *) trap 'rm -f makedefs.test makedefs.test.[co]' 1 2 3 15
+	     cat >makedefs.test.c <<'EOF'
+#include <unicode/uidna.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv)
+{
+    char buf[1024];
+    UErrorCode error = U_ZERO_ERROR;
+    UIDNAInfo info = UIDNA_INFO_INITIALIZER;
+    UIDNA * idna = uidna_openUTS46(UIDNA_DEFAULT, &error);
+    exit(14 != uidna_labelToUnicodeUTF8(idna,
+					"xn--lgbbat1ad8j", /* an arabic TLD */
+					15,
+					buf,
+					1024,
+					&info,
+					&error));
+}
+EOF
+	     ${CC-gcc} -o makedefs.test makedefs.test.c -licuuc >/dev/null 2>&1
+	     if ./makedefs.test 2>/dev/null ; then
+		 SYSLIBS="$SYSLIBS -licuuc"
+	     else
+		 CCARGS="$CCARGS -DNO_EAI"
+             fi
+	     rm -f makedefs.test makedefs.test.[co]
+esac
+
 #
 # OpenSSL has no configuration query utility, but we don't try to
 # guess. We assume includes in /usr/include/openssl and libraries in
diff --git a/src/bounce/bounce_notify_util.c b/src/bounce/bounce_notify_util.c
index 9cdf264..f1eb2ff 100644
--- a/src/bounce/bounce_notify_util.c
+++ b/src/bounce/bounce_notify_util.c
@@ -251,6 +251,7 @@ static BOUNCE_INFO *bounce_mail_alloc(const char *service,
     bounce_info->rcpt_buf = rcpt_buf;
     bounce_info->dsn_buf = dsn_buf;
     bounce_info->log_handle = log_handle;
+    bounce_info->smtputf8 = 0;
 
     /*
      * RFC 1894: diagnostic-type is an RFC 822 atom. We use X-$mail_name and
@@ -332,6 +333,19 @@ static BOUNCE_INFO *bounce_mail_alloc(const char *service,
 				      STR(bounce_info->buf) :
 				      mail_addr_mail_daemon(), 0);
 	    }
+	    
+	    /*
+	     * Information for RFC 6533 Content-Type choice.
+	     */
+	    else if (rec_type = REC_TYPE_ATTR) {
+		char *attr_name;
+		char *attr_value;
+
+		if (split_nameval(STR(bounce_info->buf),
+				  &attr_name, &attr_value) == 0 &&
+		    rec_attr_map(attr_name) == REC_TYPE_SMTPUTF8)
+		    bounce_info->smtputf8 = 1;
+	    }
 
 	    /*
 	     * Backwards compatibility: no data offset in SIZE record.
@@ -344,10 +358,6 @@ static BOUNCE_INFO *bounce_mail_alloc(const char *service,
 		bounce_info->orig_offs = vstream_ftell(bounce_info->orig_fp);
 		break;
 	    }
-	    if (bounce_info->orig_offs > 0
-		&& bounce_info->arrival_time > 0
-		&& VSTRING_LEN(bounce_info->sender) > 0)
-		break;
 	}
     }
     return (bounce_info);
@@ -602,7 +612,8 @@ int     bounce_header_dsn(VSTREAM *bounce, BOUNCE_INFO *bounce_info)
     post_mail_fprintf(bounce, "--%s", bounce_info->mime_boundary);
     post_mail_fprintf(bounce, "Content-Description: %s",
 		      "Delivery report");
-    post_mail_fprintf(bounce, "Content-Type: %s", "message/delivery-status");
+    post_mail_fprintf(bounce, "Content-Type: message/%sdelivery-status",
+		      bounce_info->smtputf8 ? "global-" : "");
 
     /*
      * According to RFC 1894: The body of a message/delivery-status consists
@@ -638,7 +649,9 @@ int     bounce_recipient_dsn(VSTREAM *bounce, BOUNCE_INFO *bounce_info)
     DSN    *dsn = &bounce_info->dsn_buf->dsn;
 
     post_mail_fputs(bounce, "");
-    post_mail_fprintf(bounce, "Final-Recipient: rfc822; %s", rcpt->address);
+    post_mail_fprintf(bounce, "Final-Recipient: %s; %s",
+		      uses_utf_8(rcpt->address) ? "utf-8" : "rfc822",
+		      rcpt->address);
 
     /*
      * XXX DSN
@@ -662,7 +675,8 @@ int     bounce_recipient_dsn(VSTREAM *bounce, BOUNCE_INFO *bounce_info)
     if (NON_NULL_EMPTY(rcpt->dsn_orcpt)) {
 	post_mail_fprintf(bounce, "Original-Recipient: %s", rcpt->dsn_orcpt);
     } else if (NON_NULL_EMPTY(rcpt->orig_addr)) {
-	post_mail_fprintf(bounce, "Original-Recipient: rfc822; %s",
+	post_mail_fprintf(bounce, "Original-Recipient: %s; %s",
+			  uses_utf_8(rcpt->orig_addr) ? "utf-8" : "rfc822",
 			  rcpt->orig_addr);
     }
     post_mail_fprintf(bounce, "Action: %s",
@@ -755,9 +769,14 @@ int     bounce_original(VSTREAM *bounce, BOUNCE_INFO *bounce_info,
 		      "Undelivered " : "",
 		      headers_only == DSN_RET_HDRS ?
 		      "Message Headers" : "Message");
-    post_mail_fprintf(bounce, "Content-Type: %s",
-		      headers_only == DSN_RET_HDRS ?
-		      "text/rfc822-headers" : "message/rfc822");
+    if (bounce_info->smtputf8)
+	post_mail_fprintf(bounce, "Content-Type: message/%s",
+			  headers_only == DSN_RET_HDRS ?
+			  "global-headers" : "global");
+    else
+	post_mail_fprintf(bounce, "Content-Type: %s",
+			  headers_only == DSN_RET_HDRS ?
+			  "text/rfc822-headers" : "message/rfc822");
     if (bounce_info->mime_encoding)
 	post_mail_fprintf(bounce, "Content-Transfer-Encoding: %s",
 			  bounce_info->mime_encoding);
diff --git a/src/bounce/bounce_service.h b/src/bounce/bounce_service.h
index 0a9bc4d..f40e206 100644
--- a/src/bounce/bounce_service.h
+++ b/src/bounce/bounce_service.h
@@ -84,6 +84,7 @@ typedef struct {
     DSN_BUF *dsn_buf;			/* delivery status info */
     BOUNCE_LOG *log_handle;		/* open logfile */
     char   *mail_name;			/* $mail_name, cooked */
+    int     smtputf8;			/* 0 for RFC1984, 1 for 6533 */     
 } BOUNCE_INFO;
 
  /* */
diff --git a/src/cleanup/cleanup_milter.c b/src/cleanup/cleanup_milter.c
index db38c91..a75f213 100644
--- a/src/cleanup/cleanup_milter.c
+++ b/src/cleanup/cleanup_milter.c
@@ -107,6 +107,7 @@
 #include <quote_821_local.h>
 #include <dsn_util.h>
 #include <xtext.h>
+#include <uxtext.h>
 
 /* Application-specific. */
 
@@ -1419,18 +1420,32 @@ static const char *cleanup_add_rcpt_par(void *context, const char *ext_rcpt,
 		    msg_warn("%s: Bad NOTIFY parameter from MILTER: \"%.100s\"",
 			     state->queue_id, arg);
 	    } else if (strncasecmp(arg, "ORCPT=", 6) == 0) {	/* RFC 3461 */
+		int good = 0;
 		if (state->milter_orcpt_buf == 0)
 		    state->milter_orcpt_buf = vstring_alloc(100);
 		if (dsn_orcpt_info
 		    || (type_len = strcspn(arg_val = arg + 6, ";")) == 0
-		    || (arg_val)[type_len] != ';'
-		    || xtext_unquote_append(
+		    || (arg_val)[type_len] != ';') {
+		    int good = 1;
+		    if (strncasecmp(arg_val, "utf-8", 5) == 0) {
+			if (uxtext_unquote_append(
 				    vstring_sprintf(state->milter_orcpt_buf,
 						    "%.*s;", (int) type_len,
 						    arg_val),
-					    arg_val + type_len + 1) == 0) {
-		    msg_warn("%s: Bad ORCPT parameter from MILTER: \"%.100s\"",
-			     state->queue_id, arg);
+				    arg_val + type_len + 1) == 0)
+			    good = 0;
+		    } else {
+			if (xtext_unquote_append(
+				    vstring_sprintf(state->milter_orcpt_buf,
+						    "%.*s;", (int) type_len,
+						    arg_val),
+				    arg_val + type_len + 1) == 0)
+			    good = 0;
+		    }
+		    if (!good)
+			msg_warn("%s: Bad ORCPT parameter from MILTER: "
+				 "\"%.100s\"",
+				 state->queue_id, arg);
 		} else {
 		    dsn_orcpt_info = STR(state->milter_orcpt_buf);
 		}
diff --git a/src/global/Makefile.in b/src/global/Makefile.in
index f5799eb..f3ebc05 100644
--- a/src/global/Makefile.in
+++ b/src/global/Makefile.in
@@ -26,7 +26,7 @@ SRCS	= abounce.c anvil_clnt.c been_here.c bounce.c bounce_log.c \
 	sent.c smtp_stream.c split_addr.c string_list.c strip_addr.c \
 	sys_exits.c timed_ipc.c tok822_find.c tok822_node.c tok822_parse.c \
 	tok822_resolve.c tok822_rewrite.c tok822_tree.c trace.c \
-	user_acl.c valid_mailhost_addr.c verify.c verify_clnt.c \
+	user_acl.c uxtext.c valid_mailhost_addr.c verify.c verify_clnt.c \
 	verp_sender.c wildcard_inet_addr.c xtext.c delivered_hdr.c \
 	fold_addr.c header_body_checks.c mkmap_proxy.c data_redirect.c \
 	match_service.c mail_conf_nint.c addr_match_list.c mail_conf_nbool.c \
@@ -60,7 +60,7 @@ OBJS	= abounce.o anvil_clnt.o been_here.o bounce.o bounce_log.o \
 	sent.o smtp_stream.o split_addr.o string_list.o strip_addr.o \
 	sys_exits.o timed_ipc.o tok822_find.o tok822_node.o tok822_parse.o \
 	tok822_resolve.o tok822_rewrite.o tok822_tree.o trace.o \
-	user_acl.o valid_mailhost_addr.o verify.o verify_clnt.o \
+	user_acl.o uxtext.o valid_mailhost_addr.o verify.o verify_clnt.o \
 	verp_sender.o wildcard_inet_addr.o xtext.o delivered_hdr.o \
 	fold_addr.o header_body_checks.o mkmap_proxy.o data_redirect.o \
 	match_service.o mail_conf_nint.o addr_match_list.o mail_conf_nbool.o \
@@ -88,7 +88,7 @@ HDRS	= abounce.h anvil_clnt.h been_here.h bounce.h bounce_log.h \
 	rec_type.h recipient_list.h record.h resolve_clnt.h resolve_local.h \
 	rewrite_clnt.h scache.h sent.h smtp_stream.h split_addr.h \
 	string_list.h strip_addr.h sys_exits.h timed_ipc.h tok822.h \
-	trace.h user_acl.h valid_mailhost_addr.h verify.h verify_clnt.h \
+	trace.h user_acl.h uxtext.h valid_mailhost_addr.h verify.h verify_clnt.h \
 	verp_sender.h wildcard_inet_addr.h xtext.h delivered_hdr.h \
 	fold_addr.h header_body_checks.h data_redirect.h match_service.h \
 	addr_match_list.h smtp_reply_footer.h safe_ultostr.h \
@@ -257,6 +257,11 @@ strip_addr: $(LIB) $(LIBS)
 	$(CC) -DTEST $(CFLAGS) -o $@ $@.c $(LIB) $(LIBS) $(SYSLIBS)
 	mv junk $@.o
 
+uxtext: $(LIB) $(LIBS)
+	mv $@.o junk
+	$(CC) $(CFLAGS) -DTEST -o $@ $@.c $(LIB) $(LIBS) $(SYSLIBS)
+	mv junk $@.o
+
 verify_clnt: $(LIB) $(LIBS)
 	mv $@.o junk
 	$(CC) $(CFLAGS) -DTEST -o $@ $@.c $(LIB) $(LIBS) $(SYSLIBS)
diff --git a/src/global/deliver_request.c b/src/global/deliver_request.c
index e32e82f..fd60386 100644
--- a/src/global/deliver_request.c
+++ b/src/global/deliver_request.c
@@ -209,6 +209,7 @@ static int deliver_request_get(VSTREAM *stream, DELIVER_REQUEST *request)
     static RCPT_BUF *rcpt_buf;
     int     rcpt_count;
     int     dsn_ret;
+    int     smtputf8 = 0;
 
     /*
      * Initialize. For some reason I wanted to allow for multiple instances
@@ -250,6 +251,7 @@ static int deliver_request_get(VSTREAM *stream, DELIVER_REQUEST *request)
 		  ATTR_TYPE_STR, MAIL_ATTR_SENDER, address,
 		  ATTR_TYPE_STR, MAIL_ATTR_DSN_ENVID, dsn_envid,
 		  ATTR_TYPE_INT, MAIL_ATTR_DSN_RET, &dsn_ret,
+		  ATTR_TYPE_INT, MAIL_ATTR_SMTPUTF8, &smtputf8,
 	       ATTR_TYPE_FUNC, msg_stats_scan, (void *) &request->msg_stats,
     /* XXX Should be encapsulated with ATTR_TYPE_FUNC. */
 		  ATTR_TYPE_STR, MAIL_ATTR_LOG_CLIENT_NAME, client_name,
@@ -265,7 +267,7 @@ static int deliver_request_get(VSTREAM *stream, DELIVER_REQUEST *request)
 		  ATTR_TYPE_STR, MAIL_ATTR_LOG_IDENT, log_ident,
 		  ATTR_TYPE_STR, MAIL_ATTR_RWR_CONTEXT, rewrite_context,
 		  ATTR_TYPE_INT, MAIL_ATTR_RCPT_COUNT, &rcpt_count,
-		  ATTR_TYPE_END) != 22) {
+		  ATTR_TYPE_END) != 23) {
 	msg_warn("%s: error receiving common attributes", myname);
 	return (-1);
     }
@@ -294,6 +296,8 @@ static int deliver_request_get(VSTREAM *stream, DELIVER_REQUEST *request)
     request->rewrite_context = mystrdup(vstring_str(rewrite_context));
     request->dsn_envid = mystrdup(vstring_str(dsn_envid));
     request->dsn_ret = dsn_ret;
+    if(smtputf8)
+	request->flags |= DEL_REQ_FLAG_SMTPUTF8;
 
     /*
      * Extract the recipient offset and address list. Skip over any
@@ -363,6 +367,7 @@ static DELIVER_REQUEST *deliver_request_alloc(void)
 
     request = (DELIVER_REQUEST *) mymalloc(sizeof(*request));
     request->fp = 0;
+    request->flags = 0;
     request->queue_name = 0;
     request->queue_id = 0;
     request->nexthop = 0;
diff --git a/src/global/deliver_request.h b/src/global/deliver_request.h
index d2ca771..2abf945 100644
--- a/src/global/deliver_request.h
+++ b/src/global/deliver_request.h
@@ -73,6 +73,8 @@ typedef struct DELIVER_REQUEST {
 #define DEL_REQ_FLAG_CONN_LOAD	(1<<11)	/* Consult opportunistic cache */
 #define DEL_REQ_FLAG_CONN_STORE	(1<<12)	/* Update opportunistic cache */
 
+#define DEL_REQ_FLAG_SMTPUTF8	(1<<13)	/* Delivery requires SMTPUTF8 */
+
  /*
   * Cache Load and Store as value or mask. Use explicit _MASK for multi-bit
   * values.
diff --git a/src/global/ehlo_mask.c b/src/global/ehlo_mask.c
index 9c60dc7..392e9d2 100644
--- a/src/global/ehlo_mask.c
+++ b/src/global/ehlo_mask.c
@@ -75,6 +75,7 @@ static const NAME_MASK ehlo_mask_table[] = {
     "STARTTLS", EHLO_MASK_STARTTLS,
     "ENHANCEDSTATUSCODES", EHLO_MASK_ENHANCEDSTATUSCODES,
     "DSN", EHLO_MASK_DSN,
+    "SMTPUTF8", EHLO_MASK_SMTPUTF8,
     "SILENT-DISCARD", EHLO_MASK_SILENT,	/* XXX In-band signaling */
     0,
 };
diff --git a/src/global/ehlo_mask.h b/src/global/ehlo_mask.h
index 62256f1..3ef2a2d 100644
--- a/src/global/ehlo_mask.h
+++ b/src/global/ehlo_mask.h
@@ -27,6 +27,7 @@
 #define EHLO_MASK_XFORWARD	(1<<9)
 #define EHLO_MASK_ENHANCEDSTATUSCODES	(1<<10)
 #define EHLO_MASK_DSN		(1<<11)
+#define EHLO_MASK_SMTPUTF8	(1<<12)
 #define EHLO_MASK_SILENT	(1<<15)
 
 extern int ehlo_mask(const char *);
diff --git a/src/global/mail_params.c b/src/global/mail_params.c
index f322af6..7859362 100644
--- a/src/global/mail_params.c
+++ b/src/global/mail_params.c
@@ -687,6 +687,9 @@ void    mail_params_init()
      * Variables whose defaults are determined at runtime. Some sites use
      * short hostnames in the host table; some sites name their system after
      * the domain.
+     *
+     * Postfix does not allow an IDN domain as hostname, due to
+     * RFC6531 section 3.7.1.
      */
     get_mail_conf_str_fn_table(function_str_defaults);
     if (!valid_hostname(var_myhostname, DO_GRIPE))
diff --git a/src/global/mail_proto.h b/src/global/mail_proto.h
index 976b125..dc73398 100644
--- a/src/global/mail_proto.h
+++ b/src/global/mail_proto.h
@@ -246,6 +246,11 @@ extern char *mail_pathname(const char *, const char *);
 #define MAIL_ATTR_DSN_ORCPT	"dsn_orig_rcpt"	/* dsn original recipient */
 
  /*
+  * RFC6531 support.
+  */
+#define MAIL_ATTR_SMTPUTF8	"smtputf8"	/* unicode or ascii/mime */
+
+ /*
   * TLSPROXY support.
   */
 #define MAIL_ATTR_REMOTE_ENDPT	"remote_endpoint"	/* name[addr]:port */
diff --git a/src/global/rec_attr_map.c b/src/global/rec_attr_map.c
index e98dde8..3dc9a92 100644
--- a/src/global/rec_attr_map.c
+++ b/src/global/rec_attr_map.c
@@ -48,6 +48,8 @@ int     rec_attr_map(const char *attr_name)
 	return (REC_TYPE_DSN_RET);
     } else if (strcmp(attr_name, MAIL_ATTR_CREATE_TIME) == 0) {
 	return (REC_TYPE_CTIME);
+    } else if (strcmp(attr_name, MAIL_ATTR_SMTPUTF8) == 0) {
+	return (REC_TYPE_SMTPUTF8);
     } else {
 	return (0);
     }
diff --git a/src/global/rec_type.c b/src/global/rec_type.c
index 1ce2111..013f967 100644
--- a/src/global/rec_type.c
+++ b/src/global/rec_type.c
@@ -71,6 +71,7 @@ REC_TYPE_NAME rec_type_names[] = {
     REC_TYPE_DSN_ENVID, "dsn_envelope_id",
     REC_TYPE_DSN_ORCPT, "dsn_original_recipient",
     REC_TYPE_DSN_NOTIFY, "dsn_notify_flags",
+    REC_TYPE_SMTPUTF8, "smtputf8",
     0, 0,
 };
 
diff --git a/src/global/rec_type.h b/src/global/rec_type.h
index f6668cd..8e82482 100644
--- a/src/global/rec_type.h
+++ b/src/global/rec_type.h
@@ -74,6 +74,8 @@
 
 #define REC_TYPE_MILT_COUNT	'm'
 
+#define REC_TYPE_SMTPUTF8	'8'	/* message uses UTF8 addresses etc */
+
 #define REC_TYPE_END	'E'		/* terminator, required */
 
  /*
diff --git a/src/global/tok822_parse.c b/src/global/tok822_parse.c
index 4376802..6ff8fe6 100644
--- a/src/global/tok822_parse.c
+++ b/src/global/tok822_parse.c
@@ -434,7 +434,7 @@ TOK822 *tok822_scan_limit(const char *str, TOK822 **tailp, int tok_count_limit)
 
     /*
      * XXX 2822 new feature: Section 4.1 allows "." to appear in a phrase (to
-     * allow for forms such as: Johnny B. Goode <johhny@domain.org>. I cannot
+     * allow for forms such as: Johnny B. Goode <johnny@domain.org>. I cannot
      * handle that at the tokenizer level - it is not context sensitive. And
      * to fix this at the parser level requires radical changes to preserve
      * white space as part of the token stream. Thanks a lot, people.
diff --git a/src/global/uxtext.c b/src/global/uxtext.c
new file mode 100644
index 0000000..9a41de8
--- /dev/null
+++ b/src/global/uxtext.c
@@ -0,0 +1,254 @@
+/*++
+/* NAME
+/*	uxtext 3
+/* SUMMARY
+/*	quote/unquote text, xtext style.
+/* SYNOPSIS
+/*	#include <uxtext.h>
+/*
+/*	VSTRING	*uxtext_quote(quoted, unquoted, special)
+/*	VSTRING	*quoted;
+/*	const char *unquoted;
+/*	const char *special;
+/*
+/*	VSTRING	*uxtext_quote_append(unquoted, quoted, special)
+/*	VSTRING	*unquoted;
+/*	const char *quoted;
+/*	const char *special;
+/*
+/*	VSTRING	*uxtext_unquote(unquoted, quoted)
+/*	VSTRING	*unquoted;
+/*	const char *quoted;
+/*
+/*	VSTRING	*uxtext_unquote_append(unquoted, quoted)
+/*	VSTRING	*unquoted;
+/*	const char *quoted;
+/* DESCRIPTION
+/*	uxtext_quote() takes a null-terminated UTF8 string and replaces
+/*      characters \, <33(10) and >126(10), as well as characters specified
+/*	with "special" by \x{XX}, XX being a 2-6-digit uppercase hexadecimal
+/*	equivalent.
+/*
+/*	uxtext_quote_append() is like uxtext_quote(), but appends the conversion
+/*	result to the result buffer.
+/*
+/*	uxtext_unquote() performs the opposite transformation. This function
+/*	understands lowercase, uppercase, and mixed case +\x{XX...} sequences.
+/*	The result value is the unquoted argument in case of success, a null
+/*	pointer otherwise.
+/*
+/*	uxtext_unquote_append() is like uxtext_unquote(), but appends
+/*	the conversion result to the result buffer.
+/* BUGS
+/*	This module cannot process null characters in data.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <string.h>
+#include <ctype.h>
+
+/* Utility library. */
+
+#include "msg.h"
+#include "vstring.h"
+#include "uxtext.h"
+
+/* Application-specific. */
+
+#define STR(x)	vstring_str(x)
+#define LEN(x)	VSTRING_LEN(x)
+
+/* uxtext_quote_append - append unquoted data to quoted data */
+
+VSTRING *uxtext_quote_append(VSTRING *quoted, const char *unquoted,
+			            const char *special)
+{
+    unsigned const char *cp;
+    int     ch;
+
+    for (cp = (unsigned const char *)unquoted; (ch = *cp) != 0; cp++) {
+	if (ch != '+' && ch > 32 && ch < 127
+	    && (*special == 0 || strchr(special, ch) == 0)) {
+	    VSTRING_ADDCH(quoted, ch);
+	} else {
+	    /* had RFC6533 been written like 6531 and 652, this else
+	       clause would be one line long. */
+	    int unicode = 0;
+	    int pick = 0;
+
+	    if ( ch < 0x80 ) {
+		// 0000 0000-0000 007F   0xxxxxxx
+		unicode = ch;
+	    } else if ((ch & 0xe0) == 0xc0) {
+		// 0000 0080-0000 07FF   110xxxxx 10xxxxxx
+		unicode = (ch & 0x1f);
+		pick = 1;
+	    } else if ((ch & 0xf0) == 0xe0) {
+		// 0000 0800-0000 FFFF   1110xxxx 10xxxxxx 10xxxxxx
+		unicode = (ch & 0x0f);
+		pick = 2;
+	    } else if ((ch & 0xf8) == 0xf0) {
+		// 0001 0000-001F FFFF   11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+		unicode = (ch & 0x07);
+		pick = 3;
+	    } else if ((ch & 0xfc) == 0xf8) {
+		// 0020 0000-03FF FFFF   111110xx 10xxxxxx 10xxxxxx ... 10xxxxxx
+		unicode = (ch & 0x03);
+		pick = 4;
+	    } else if ((ch & 0xfe) == 0xfc) {
+		// 0400 0000-7FFF FFFF   1111110x 10xxxxxx ... 10xxxxxx
+		unicode = (ch & 0x01);
+		pick = 5;
+	    } else {
+		return (0);
+	    }
+	    while (pick > 0) {
+		ch = *++cp;
+		if ((ch & 0xc0) != 0x80)
+		    return (0);
+		unicode = unicode << 6 | (ch & 0x3f);
+		pick--;
+	    }
+	    vstring_sprintf_append(quoted, "\\x{%02X}", unicode);
+	}
+    }
+    VSTRING_TERMINATE(quoted);
+    return (quoted);
+}
+
+/* uxtext_quote - unquoted data to quoted */
+
+VSTRING *uxtext_quote(VSTRING *quoted, const char *unquoted, const char *special)
+{
+    VSTRING_RESET(quoted);
+    uxtext_quote_append(quoted, unquoted, special);
+    return (quoted);
+}
+
+/* uxtext_unquote_append - quoted data to unquoted */
+
+VSTRING *uxtext_unquote_append(VSTRING *unquoted, const char *quoted)
+{
+    const char *cp;
+    int     ch;
+
+    for (cp = quoted; (ch = *cp) != 0; cp++) {
+	if (ch == '\\' && cp[1] == 'x' && cp[2] == '{') {
+	    cp += 2;
+	    int unicode = 0;
+	    while ((ch = *++cp) != '}') {
+		if (ISDIGIT(ch))
+		    unicode = (unicode << 4) + (ch-'0');
+		else if (ch >= 'a' && ch <= 'f')
+		    unicode = (unicode << 4) + (ch-'a'+10);
+		else if (ch >= 'A' && ch <= 'F')
+		    unicode = (unicode << 4) + (ch-'A'+10);
+		else
+		    return (0); /* also covers the null terminator */
+		if (unicode > 0x10ffff)
+		    return (0);
+	    }
+	    
+	    /* the following block is from
+	     * https://github.com/aox/aox/blob/master/encodings/utf.cpp,
+	     * with permission by the authors.
+	     */
+	    if ( unicode < 0x80 ) {
+		VSTRING_ADDCH(unquoted, (char)unicode );
+	    } else if ( unicode < 0x800 ) {
+		VSTRING_ADDCH(unquoted, 0xc0 | ((char)(unicode >> 6)));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode & 0x3f)));
+	    } else if ( unicode < 0x10000 ) {
+		VSTRING_ADDCH(unquoted, 0xe0 | ((char)(unicode >> 12)));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 6) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode & 0x3f)));
+	    } else if ( unicode < 0x200000 ) {
+		VSTRING_ADDCH(unquoted, 0xf0 | ((char)(unicode >> 18)));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 12) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 6) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode & 0x3f)));
+	    } else if ( unicode < 0x4000000 ) {
+		VSTRING_ADDCH(unquoted, 0xf8 | ((char)(unicode >> 24)));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 18) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 12) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 6) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode & 0x3f)));
+	    } else {
+		VSTRING_ADDCH(unquoted, 0xfc | ((char)(unicode >> 30)));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 24) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 18) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 12) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode >> 6) & 0x3f));
+		VSTRING_ADDCH(unquoted, 0x80 | ((char)(unicode & 0x3f)));
+	    }
+	} else {
+	    VSTRING_ADDCH(unquoted, ch);
+	}
+    }
+    VSTRING_TERMINATE(unquoted);
+    return (unquoted);
+}
+
+/* uxtext_unquote - quoted data to unquoted */
+
+VSTRING *uxtext_unquote(VSTRING *unquoted, const char *quoted)
+{
+    VSTRING_RESET(unquoted);
+    uxtext_unquote_append(unquoted, quoted);
+    return (unquoted);
+}
+
+#ifdef TEST
+
+ /*
+  * Proof-of-concept test program: convert to quoted and back.
+  */
+#include <vstream.h>
+
+#define BUFLEN 1024
+
+static ssize_t read_buf(VSTREAM *fp, VSTRING *buf)
+{
+    ssize_t len;
+
+    VSTRING_RESET(buf);
+    len = vstream_fread(fp, STR(buf), vstring_avail(buf));
+    VSTRING_AT_OFFSET(buf, len);		/* XXX */
+    VSTRING_TERMINATE(buf);
+    return (len);
+}
+
+int     main(int unused_argc, char **unused_argv)
+{
+    VSTRING *unquoted = vstring_alloc(BUFLEN);
+    VSTRING *quoted = vstring_alloc(100);
+    ssize_t len;
+
+    while ((len = read_buf(VSTREAM_IN, unquoted)) > 0) {
+	uxtext_quote(quoted, STR(unquoted), "+=");
+	if (uxtext_unquote(unquoted, STR(quoted)) == 0)
+	    msg_fatal("bad input: %.100s", STR(quoted));
+	if (LEN(unquoted) != len)
+	    msg_fatal("len %ld != unquoted len %ld",
+		      (long) len, (long) LEN(unquoted));
+	if (vstream_fwrite(VSTREAM_OUT, STR(unquoted), LEN(unquoted)) != LEN(unquoted))
+	    msg_fatal("write error: %m");
+    }
+    vstream_fflush(VSTREAM_OUT);
+    vstring_free(unquoted);
+    vstring_free(quoted);
+    return (0);
+}
+
+#endif
diff --git a/src/global/uxtext.h b/src/global/uxtext.h
new file mode 100644
index 0000000..add8d39
--- /dev/null
+++ b/src/global/uxtext.h
@@ -0,0 +1,38 @@
+#ifndef _XTEXT_H_INCLUDED_
+#define _XTEXT_H_INCLUDED_
+
+/*++
+/* NAME
+/*	uxtext 3h
+/* SUMMARY
+/*	quote/unquote text, RFC 6533 style.
+/* SYNOPSIS
+/*	#include <uxtext.h>
+/* DESCRIPTION
+/* .nf
+
+ /*
+  * Utility library.
+  */
+#include <vstring.h>
+
+ /*
+  * External interface.
+  */
+extern VSTRING *uxtext_quote(VSTRING *, const char *, const char *);
+extern VSTRING *uxtext_quote_append(VSTRING *, const char *, const char *);
+extern VSTRING *uxtext_unquote(VSTRING *, const char *);
+extern VSTRING *uxtext_unquote_append(VSTRING *, const char *);
+
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+#endif
diff --git a/src/oqmgr/qmgr.h b/src/oqmgr/qmgr.h
index 802ce12..e51b438 100644
--- a/src/oqmgr/qmgr.h
+++ b/src/oqmgr/qmgr.h
@@ -298,6 +298,7 @@ struct QMGR_MESSAGE {
     char   *sender;			/* complete address */
     char   *dsn_envid;			/* DSN envelope ID */
     int     dsn_ret;			/* DSN headers/full */
+    int     smtputf8;			/* requires unicode */
     char   *verp_delims;		/* VERP delimiters */
     char   *filter_xport;		/* filtering transport */
     char   *inspect_xport;		/* inspecting transport */
diff --git a/src/oqmgr/qmgr_deliver.c b/src/oqmgr/qmgr_deliver.c
index ce81fd7..6d14a00 100644
--- a/src/oqmgr/qmgr_deliver.c
+++ b/src/oqmgr/qmgr_deliver.c
@@ -165,6 +165,7 @@ static int qmgr_deliver_send_request(QMGR_ENTRY *entry, VSTREAM *stream)
 	       ATTR_TYPE_STR, MAIL_ATTR_SENDER, sender,
 	       ATTR_TYPE_STR, MAIL_ATTR_DSN_ENVID, message->dsn_envid,
 	       ATTR_TYPE_INT, MAIL_ATTR_DSN_RET, message->dsn_ret,
+	       ATTR_TYPE_INT, MAIL_ATTR_SMTPUTF8, message->smtputf8,
 	       ATTR_TYPE_FUNC, msg_stats_print, (void *) &stats,
     /* XXX Should be encapsulated with ATTR_TYPE_FUNC. */
 	     ATTR_TYPE_STR, MAIL_ATTR_LOG_CLIENT_NAME, message->client_name,
diff --git a/src/oqmgr/qmgr_message.c b/src/oqmgr/qmgr_message.c
index e2f9237..0608356 100644
--- a/src/oqmgr/qmgr_message.c
+++ b/src/oqmgr/qmgr_message.c
@@ -168,6 +168,7 @@ static QMGR_MESSAGE *qmgr_message_create(const char *queue_name,
     message->sender = 0;
     message->dsn_envid = 0;
     message->dsn_ret = 0;
+    message->smtputf8 = 0;
     message->filter_xport = 0;
     message->inspect_xport = 0;
     message->redirect_addr = 0;
@@ -605,6 +606,9 @@ static int qmgr_message_read(QMGR_MESSAGE *message)
 		    message->dsn_ret = n;
 	    }
 	}
+	if (rec_type == REC_TYPE_SMTPUTF8) {
+	    message->smtputf8 = 1;
+	}
 	if (rec_type == REC_TYPE_ATTR) {
 	    /* Allow extra segment to override envelope segment info. */
 	    if (strcmp(name, MAIL_ATTR_ENCODING) == 0) {
diff --git a/src/postscreen/postscreen_dnsbl.c b/src/postscreen/postscreen_dnsbl.c
index ef3140b..3656c6f 100644
--- a/src/postscreen/postscreen_dnsbl.c
+++ b/src/postscreen/postscreen_dnsbl.c
@@ -241,7 +241,7 @@ static void psc_dnsbl_add_site(const char *site)
 	if ((parse_err = ip_match_parse(byte_codes, pattern_text)) != 0)
 	    msg_fatal("bad DNSBL filter syntax: %s", parse_err);
     }
-    if (valid_hostname(saved_site, DO_GRIPE) == 0)
+    if (valid_hostname(saved_site, DO_GRIPE) == 0)  /* no IDN support for DNSbls */
 	msg_fatal("bad DNSBL domain name \"%s\" in \"%s\"",
 		  saved_site, site);
 
diff --git a/src/qmgr/qmgr.h b/src/qmgr/qmgr.h
index 6737e42..c9699e7 100644
--- a/src/qmgr/qmgr.h
+++ b/src/qmgr/qmgr.h
@@ -268,7 +268,7 @@ extern void qmgr_queue_suspend(QMGR_QUEUE *, int);
   * "not throttled". It was natural to encode these in the queue window size.
   * After 10 years it's not practical to rip out all the working code and
   * change representations, so we just clean up the names a little.
-  * 
+  *
   * Note: only the "ready" state can reach every state (including itself);
   * non-ready states can reach only the "ready" state. Other transitions are
   * forbidden, because they would result in dangling event handlers.
@@ -343,6 +343,7 @@ struct QMGR_MESSAGE {
     char   *sender;			/* complete address */
     char   *dsn_envid;			/* DSN envelope ID */
     int     dsn_ret;			/* DSN headers/full */
+    int     smtputf8;			/* requires unicode */
     char   *verp_delims;		/* VERP delimiters */
     char   *filter_xport;		/* filtering transport */
     char   *inspect_xport;		/* inspecting transport */
diff --git a/src/qmgr/qmgr_deliver.c b/src/qmgr/qmgr_deliver.c
index 2fbb049..841a227 100644
--- a/src/qmgr/qmgr_deliver.c
+++ b/src/qmgr/qmgr_deliver.c
@@ -170,6 +170,7 @@ static int qmgr_deliver_send_request(QMGR_ENTRY *entry, VSTREAM *stream)
 	       ATTR_TYPE_STR, MAIL_ATTR_SENDER, sender,
 	       ATTR_TYPE_STR, MAIL_ATTR_DSN_ENVID, message->dsn_envid,
 	       ATTR_TYPE_INT, MAIL_ATTR_DSN_RET, message->dsn_ret,
+	       ATTR_TYPE_INT, MAIL_ATTR_SMTPUTF8, message->smtputf8,
 	       ATTR_TYPE_FUNC, msg_stats_print, (void *) &stats,
     /* XXX Should be encapsulated with ATTR_TYPE_FUNC. */
 	     ATTR_TYPE_STR, MAIL_ATTR_LOG_CLIENT_NAME, message->client_name,
diff --git a/src/qmgr/qmgr_message.c b/src/qmgr/qmgr_message.c
index e6bbaf6..b4807cf 100644
--- a/src/qmgr/qmgr_message.c
+++ b/src/qmgr/qmgr_message.c
@@ -179,6 +179,7 @@ static QMGR_MESSAGE *qmgr_message_create(const char *queue_name,
     message->sender = 0;
     message->dsn_envid = 0;
     message->dsn_ret = 0;
+    message->smtputf8 = 0;
     message->filter_xport = 0;
     message->inspect_xport = 0;
     message->redirect_addr = 0;
@@ -646,6 +647,9 @@ static int qmgr_message_read(QMGR_MESSAGE *message)
 		    message->dsn_ret = n;
 	    }
 	}
+	if (rec_type == REC_TYPE_SMTPUTF8) {
+	    message->smtputf8 = 1;
+	}
 	if (rec_type == REC_TYPE_ATTR) {
 	    /* Allow extra segment to override envelope segment info. */
 	    if (strcmp(name, MAIL_ATTR_ENCODING) == 0) {
diff --git a/src/sendmail/sendmail.c b/src/sendmail/sendmail.c
index 83dac65..f23dc9f 100644
--- a/src/sendmail/sendmail.c
+++ b/src/sendmail/sendmail.c
@@ -609,6 +609,7 @@ static void output_header(void *context, int header_class,
     }
 }
 
+
 /* enqueue - post one message */
 
 static void enqueue(const int flags, const char *encoding,
@@ -641,6 +642,7 @@ static void enqueue(const int flags, const char *encoding,
     const char *errstr;
     int     addr_count;
     int     level;
+    int     smtputf8 = 0;
     static NAME_CODE sm_fix_eol_table[] = {
 	SM_FIX_EOL_ALWAYS, STRIP_CR_DO,
 	SM_FIX_EOL_STRICT, STRIP_CR_DUNNO,
@@ -692,6 +694,8 @@ static void enqueue(const int flags, const char *encoding,
 	saved_sender = mystrdup(sender);
     }
 
+    smtputf8 |= uses_utf_8(saved_sender);
+
     /*
      * Let the postdrop command open the queue file for us, and sanity check
      * the content. XXX Make postdrop a manifest constant.
@@ -760,6 +764,7 @@ static void enqueue(const int flags, const char *encoding,
 					 saved_sender, (long) uid);
 		    ++rcpt_count;
 		    ++addr_count;
+		    smtputf8 |= uses_utf_8(STR(buf));
 		}
 	    }
 	    tok822_free_tree(tree);
@@ -774,6 +779,17 @@ static void enqueue(const int flags, const char *encoding,
     }
 
     /*
+     * If either the sender or any recipients contain non-ascii
+     * characters, then this message has to be sent with the SMTPUTF8
+     * extension.
+     */
+
+    if(smtputf8) {
+	rec_fprintf(dst, REC_TYPE_ATTR, "%s=%d",
+		    MAIL_ATTR_SMTPUTF8, 1);
+    }
+
+    /*
      * Append the message contents to the queue file. Write chunks of at most
      * 1kbyte. Internally, we use different record types for data ending in
      * LF and for data that doesn't, so we can actually be binary transparent
diff --git a/src/smtp/smtp.h b/src/smtp/smtp.h
index ee9e506..b576c0d 100644
--- a/src/smtp/smtp.h
+++ b/src/smtp/smtp.h
@@ -221,6 +221,7 @@ typedef struct SMTP_STATE {
 #define SMTP_FEATURE_XFORWARD_PORT	(1<<18)
 #define SMTP_FEATURE_EARLY_TLS_MAIL_REPLY (1<<19)	/* CVE-2009-3555 */
 #define SMTP_FEATURE_XFORWARD_IDENT	(1<<20)
+#define SMTP_FEATURE_SMTPUTF8		(1<<21)
 
  /*
   * Features that passivate under the endpoint.
diff --git a/src/smtp/smtp_addr.c b/src/smtp/smtp_addr.c
index deba52f..ca426a8 100644
--- a/src/smtp/smtp_addr.c
+++ b/src/smtp/smtp_addr.c
@@ -96,6 +96,12 @@
 
 #include <dns.h>
 
+/* ICU, in order to do the right DNS lookups */
+
+#ifndef NO_EAI
+#include <unicode/uidna.h>
+#endif
+
 /* Application-specific. */
 
 #include "smtp.h"
@@ -340,6 +346,51 @@ static DNS_RR *smtp_truncate_self(DNS_RR *addr_list, unsigned pref)
     return (addr_list);
 }
 
+/* smtp_domain_addr - return an ASCII copy of a domain
+   
+   The caller must free the return value.
+*/
+
+char * smtp_domain_ascii(const char *name)
+{
+    char * aname;
+#ifndef NO_EAI
+    unsigned char * cp = (unsigned char *)name;
+    
+    while (cp && *cp && *cp < 128)
+	cp++;
+    
+    if (cp && *cp > 128) {
+	char buf[1024];
+	UErrorCode error = U_ZERO_ERROR;
+	UIDNAInfo info = UIDNA_INFO_INITIALIZER;
+	UIDNA * idna;
+	int anl;
+
+	idna = uidna_openUTS46(UIDNA_DEFAULT, &error);
+	anl = uidna_nameToASCII_UTF8(idna,
+				     name, strlen(name),
+				     buf, 1024,
+				     &info,
+				     &error);
+	uidna_close(idna);
+	if(U_SUCCESS(error) && info.errors == 0 && anl > 0) {
+	    aname = mymalloc(anl+1);
+	    aname[anl] = 0;
+	    strncpy(aname, buf, anl);
+	    return aname;
+	} else {
+	    msg_info("smtp_domain_ascii: "
+		     "Problem translating domain %s to IDNA form: %s",
+		     name, u_errorName(error));
+	}
+    }
+#endif
+    aname = mymalloc(strlen(name)+1);
+    strcpy(aname, name);
+    return aname;
+}
+
 /* smtp_domain_addr - mail exchanger address lookup */
 
 DNS_RR *smtp_domain_addr(char *name, DNS_RR **mxrr, int misc_flags,
@@ -351,6 +402,7 @@ DNS_RR *smtp_domain_addr(char *name, DNS_RR **mxrr, int misc_flags,
     unsigned best_pref;
     unsigned best_found;
     int     r = 0;			/* Resolver flags */
+    char *aname;
 
     dsb_reset(why);				/* Paranoia */
 
@@ -367,6 +419,8 @@ DNS_RR *smtp_domain_addr(char *name, DNS_RR **mxrr, int misc_flags,
     if (smtp_dns_support == SMTP_DNS_DNSSEC)
 	r |= RES_USE_DNSSEC;
 
+    aname = smtp_domain_ascii(name);
+
     /*
      * Look up the mail exchanger hosts listed for this name. Sort the
      * results by preference. Look up the corresponding host addresses, and
@@ -409,21 +463,21 @@ DNS_RR *smtp_domain_addr(char *name, DNS_RR **mxrr, int misc_flags,
      * at hostnames provides a partial solution for MX hosts behind a NAT
      * gateway.
      */
-    switch (dns_lookup(name, T_MX, r, &mx_names, (VSTRING *) 0, why->reason)) {
+    switch (dns_lookup(aname, T_MX, r, &mx_names, (VSTRING *) 0, why->reason)) {
     default:
 	dsb_status(why, "4.4.3");
 	if (var_ign_mx_lookup_err)
-	    addr_list = smtp_host_addr(name, misc_flags, why);
+	    addr_list = smtp_host_addr(aname, misc_flags, why);
 	break;
     case DNS_INVAL:
 	dsb_status(why, "5.4.4");
 	if (var_ign_mx_lookup_err)
-	    addr_list = smtp_host_addr(name, misc_flags, why);
+	    addr_list = smtp_host_addr(aname, misc_flags, why);
 	break;
     case DNS_FAIL:
 	dsb_status(why, "5.4.3");
 	if (var_ign_mx_lookup_err)
-	    addr_list = smtp_host_addr(name, misc_flags, why);
+	    addr_list = smtp_host_addr(aname, misc_flags, why);
 	break;
     case DNS_OK:
 	mx_names = dns_rr_sort(mx_names, dns_rr_compare_pref_any);
@@ -472,13 +526,14 @@ DNS_RR *smtp_domain_addr(char *name, DNS_RR **mxrr, int misc_flags,
 	}
 	break;
     case DNS_NOTFOUND:
-	addr_list = smtp_host_addr(name, misc_flags, why);
+	addr_list = smtp_host_addr(aname, misc_flags, why);
 	break;
     }
 
     /*
      * Clean up.
      */
+    myfree(aname);
     *found_myself |= (self != 0);
     return (addr_list);
 }
diff --git a/src/smtp/smtp_addr.h b/src/smtp/smtp_addr.h
index cf0b689..6784628 100644
--- a/src/smtp/smtp_addr.h
+++ b/src/smtp/smtp_addr.h
@@ -16,6 +16,7 @@
  /*
   * Internal interfaces.
   */
+extern char *smtp_domain_ascii(const char *);
 extern DNS_RR *smtp_host_addr(const char *, int, DSN_BUF *);
 extern DNS_RR *smtp_domain_addr(char *, DNS_RR **, int, DSN_BUF *, int *);
 
diff --git a/src/smtp/smtp_proto.c b/src/smtp/smtp_proto.c
index fbae51f..bc4f673 100644
--- a/src/smtp/smtp_proto.c
+++ b/src/smtp/smtp_proto.c
@@ -233,6 +233,7 @@ char   *xfer_request[SMTP_STATE_LAST] = {
 
 #define SMTP_MIME_DOWNGRADE(session, request) \
     (var_disable_mime_oconv == 0 \
+     && (request->flags & DEL_REQ_FLAG_SMTPUTF8) == 0 \
      && (session->features & SMTP_FEATURE_8BITMIME) == 0 \
      && strcmp(request->encoding, MAIL_ATTR_ENC_7BIT) != 0)
 
@@ -547,6 +548,9 @@ int     smtp_helo(SMTP_STATE *state)
 		} else if (strcasecmp(word, "DSN") == 0) {
 		    if ((discard_mask & EHLO_MASK_DSN) == 0)
 			session->features |= SMTP_FEATURE_DSN;
+		} else if (strcasecmp(word, "SMTPUTF8") == 0) {
+		    if ((discard_mask & EHLO_MASK_SMTPUTF8) == 0)
+			session->features |= SMTP_FEATURE_SMTPUTF8;
 		}
 		n++;
 	    }
@@ -1258,6 +1262,21 @@ static int smtp_loop(SMTP_STATE *state, NOCLOBBER int send_state,
      * The main protocol loop.
      */
     do {
+	if (send_state == SMTP_STATE_MAIL &&
+	    (request->flags & DEL_REQ_FLAG_SMTPUTF8) &&
+	    !(session->features & SMTP_FEATURE_SMTPUTF8)) {
+	    /*
+	     * The message requires unicode, the server does not
+	     * support that. This isn't going to work.
+	     */
+	    smtp_site_fail(state, DSN_BY_LOCAL_MTA,
+			   SMTP_RESP_FAKE(&fake, "5.6.7"),
+			   "SMTPUTF8 is required, "
+			   "but was not offered by host %s",
+			   session->namaddr);
+	    send_state = SMTP_STATE_ABORT;
+	    break;
+	}
 
 	/*
 	 * Build the next command.
@@ -1377,6 +1396,9 @@ static int smtp_loop(SMTP_STATE *state, NOCLOBBER int send_state,
 		    vstring_sprintf_append(next_command, " RET=%s",
 					   dsn_ret_str(request->dsn_ret));
 	    }
+	    if (request->flags & DEL_REQ_FLAG_SMTPUTF8) {
+		vstring_strcat(next_command, " SMTPUTF8");
+	    }
 
 	    /*
 	     * We authenticate the local MTA only, but not the sender.
@@ -1432,18 +1454,24 @@ static int smtp_loop(SMTP_STATE *state, NOCLOBBER int send_state,
 			    vstring_str(session->scratch));
 	    if (session->features & SMTP_FEATURE_DSN) {
 		/* XXX DSN xtext encode address value not type. */
-		if (rcpt->dsn_orcpt[0]) {
-		    xtext_quote(session->scratch, rcpt->dsn_orcpt, "+=");
-		    vstring_sprintf_append(next_command, " ORCPT=%s",
-					   vstring_str(session->scratch));
-		} else if (rcpt->orig_addr[0]) {
+		const char * orcpt = rcpt->dsn_orcpt;
+		if (!*orcpt) {
 		    quote_822_local(session->scratch, rcpt->orig_addr);
-		    vstring_sprintf(session->scratch2, "rfc822;%s",
+		    vstring_sprintf(session->scratch2, "%s;%s",
+				    uses_utf_8(vstring_str(session->scratch)) 
+				    ? "utf-8" : "rfc822",
 				    vstring_str(session->scratch));
-		    xtext_quote(session->scratch, vstring_str(session->scratch2), "+=");
-		    vstring_sprintf_append(next_command, " ORCPT=%s",
-					   vstring_str(session->scratch));
+		    orcpt = vstring_str(session->scratch2);
+		}
+		if (session->features & SMTP_FEATURE_SMTPUTF8) {
+		    vstring_strcpy(session->scratch, orcpt);
+		} else if (uses_utf_8(orcpt)) {
+		    uxtext_quote(session->scratch, orcpt, "\\");
+		} else {
+		    xtext_quote(session->scratch, orcpt, "+=");
 		}
+		vstring_sprintf_append(next_command, " ORCPT=%s",
+				       vstring_str(session->scratch));
 		if (rcpt->dsn_notify)
 		    vstring_sprintf_append(next_command, " NOTIFY=%s",
 					   dsn_notify_str(rcpt->dsn_notify));
diff --git a/src/smtp/smtp_tls_policy.c b/src/smtp/smtp_tls_policy.c
index f280810..537e264 100644
--- a/src/smtp/smtp_tls_policy.c
+++ b/src/smtp/smtp_tls_policy.c
@@ -375,7 +375,7 @@ static void tls_policy_lookup(SMTP_TLS_POLICY *tls, int *site_level,
      * 
      * XXX UNIX-domain connections query with the pathname as destination.
      */
-    if (!valid_hostname(site_name, DONT_GRIPE)) {
+    if (!valid_mail_domain(site_name, DONT_GRIPE)) {
 	tls_policy_lookup_one(tls, site_level, site_name, site_class);
 	return;
     }
diff --git a/src/smtpd/smtpd.c b/src/smtpd/smtpd.c
index fa01313..0739ae4 100644
--- a/src/smtpd/smtpd.c
+++ b/src/smtpd/smtpd.c
@@ -1791,6 +1791,8 @@ static int ehlo_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
 	EHLO_APPEND(state, "8BITMIME");
     if ((discard_mask & EHLO_MASK_DSN) == 0)
 	EHLO_APPEND(state, "DSN");
+    if ((discard_mask & EHLO_MASK_SMTPUTF8) == 0)
+	EHLO_APPEND(state, "SMTPUTF8");
 
     /*
      * Send the reply.
@@ -1971,6 +1973,13 @@ static int mail_open_stream(SMTPD_STATE *state)
 			MAIL_ATTR_ENCODING, state->encoding);
 
 	/*
+	 * Record that the message uses SMTPUTF8, if it so does.
+	 */
+	if (state->flags & SMTPD_FLAG_SMTPUTF8)
+	    rec_fprintf(state->cleanup, REC_TYPE_ATTR, "%s=%d",
+			MAIL_ATTR_SMTPUTF8, 1);
+
+	/*
 	 * Store client attributes.
 	 */
 	if (SMTPD_STAND_ALONE(state) == 0) {
@@ -2292,6 +2301,8 @@ static int mail_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
 		smtpd_chat_reply(state, "552 5.3.4 Message size exceeds file system imposed limit");
 		return (-1);
 	    }
+	} else if (strcasecmp(arg, "SMTPUTF8") == 0) { /* RFC 6531 */
+	    state->flags |= SMTPD_FLAG_SMTPUTF8;
 #ifdef USE_SASL_AUTH
 	} else if (strncasecmp(arg, "AUTH=", 5) == 0) {
 	    if ((err = smtpd_sasl_mail_opt(state, arg + 5)) != 0) {
@@ -2408,6 +2419,16 @@ static int mail_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
 	    return (-1);
 	}
     }
+    if ((state->flags & SMTPD_FLAG_SMTPUTF8) == 0) {
+	unsigned char * cp = STR(state->addr_buf);
+	while (cp && *cp && *cp < 128)
+	    cp++;
+	if(cp && *cp >= 128) {
+	    mail_reset(state);
+	    smtpd_chat_reply(state, "553 5.6.7 Must declare SMTPUTF8 to send from unicode addresses");
+	    return (-1);
+	}
+    }
 
     /*
      * Check the queue file space, if applicable. The optional before-filter
@@ -2618,13 +2639,24 @@ static int rcpt_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
 	    }
 	    vstring_strcpy(state->dsn_orcpt_buf, arg + 6);
 	    if (dsn_orcpt_addr
-	     || (coded_addr = split_at(STR(state->dsn_orcpt_buf), ';')) == 0
-		|| xtext_unquote(state->dsn_buf, coded_addr) == 0
-		|| *(dsn_orcpt_type = STR(state->dsn_orcpt_buf)) == 0) {
-		state->error_mask |= MAIL_ERROR_PROTOCOL;
-		smtpd_chat_reply(state,
-			     "501 5.5.4 Error: Bad ORCPT parameter syntax");
-		return (-1);
+		|| (coded_addr = split_at(STR(state->dsn_orcpt_buf),
+					  ';')) == 0) {
+		int good = 1;
+		if(strncasecmp(STR(state->dsn_orcpt_buf), "utf-8", 5) == 0) {
+		    if (uxtext_unquote(state->dsn_buf, coded_addr) == 0)
+			good = 0;
+		} else {
+		    if (xtext_unquote(state->dsn_buf, coded_addr) == 0
+			|| *(dsn_orcpt_type = STR(state->dsn_orcpt_buf)) == 0)
+			good = 0;
+		}
+		if (!good) {
+		    state->error_mask |= MAIL_ERROR_PROTOCOL;
+		    smtpd_chat_reply(state,
+				     "501 5.5.4 Error: "
+				     "Bad ORCPT parameter syntaxx");
+		    return (-1);
+		}
 	    }
 	    dsn_orcpt_addr = STR(state->dsn_buf);
 	    dsn_orcpt_addr_len = LEN(state->dsn_buf);
@@ -2699,6 +2731,21 @@ static int rcpt_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
     }
 
     /*
+     * Prevent mail to SMTPUTF8 addresses from senders who haven't declared
+     * that extension.
+     */
+    if ((state->flags & SMTPD_FLAG_SMTPUTF8) == 0) {
+	unsigned char * cp = argv[2].strval;
+	while (cp && *cp && *cp < 128)
+	    cp++;
+	if(cp && *cp >= 128) {
+	    mail_reset(state);
+	    smtpd_chat_reply(state, "553 5.6.7 Must declare SMTPUTF8 to send to unicode addresses");
+	    return (-1);
+	}
+    }
+
+    /*
      * Store the recipient. Remember the first one.
      * 
      * Flush recipients to maintain a stiffer coupling with the next stage and
@@ -2898,6 +2945,7 @@ static int data_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *unused_argv)
     const CLEANUP_STAT_DETAIL *detail;
     const char *rfc3848_sess;
     const char *rfc3848_auth;
+    const char *protoname;
 
 #ifdef USE_TLS
     VSTRING *peer_CN;
@@ -3055,12 +3103,22 @@ static int data_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *unused_argv)
 	else
 #endif
 	    rfc3848_auth = "";
+	/* RFC 6531 defines an "UTF8" prefix for ESMTP and LMTP, but
+	 * "UTF8" + "ESMTP" becomes "UTF8SMTP" in 6531's math, so we
+	 * have to hack here to get the WITH clause correct.
+	 */
+	if ((state->flags & SMTPD_FLAG_SMTPUTF8) == 0)
+	    protoname = state->protocol;
+	else if (state->protocol[0] == 'L')
+	    protoname = "UTF8LMTP";
+	else
+	    protoname = "UTF8SMTP";
 	if (state->rcpt_count == 1 && state->recipient) {
 	    out_fprintf(out_stream, REC_TYPE_NORM,
 			state->cleanup ? "\tby %s (%s) with %s%s%s id %s" :
 			"\tby %s (%s) with %s%s%s",
 			var_myhostname, var_mail_name,
-			state->protocol, rfc3848_sess,
+			protoname, rfc3848_sess,
 			rfc3848_auth, state->queue_id);
 	    quote_822_local(state->buffer, state->recipient);
 	    out_fprintf(out_stream, REC_TYPE_NORM,
@@ -3071,7 +3129,7 @@ static int data_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *unused_argv)
 			state->cleanup ? "\tby %s (%s) with %s%s%s id %s;" :
 			"\tby %s (%s) with %s%s%s;",
 			var_myhostname, var_mail_name,
-			state->protocol, rfc3848_sess,
+			protoname, rfc3848_sess,
 			rfc3848_auth, state->queue_id);
 	    out_fprintf(out_stream, REC_TYPE_NORM,
 			"\t%s", mail_date(state->arrival_time.tv_sec));
@@ -3440,6 +3498,8 @@ static int vrfy_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
 	smtpd_chat_reply(state, "%s", err);
 	return (-1);
     }
+    if (argc >= 3 && strcasecmp(argv[argc - 1].strval, "smtputf8") == 0)
+	argc--;
     if (argc > 2)
 	collapse_args(argc - 1, argv + 1);
     if (extract_addr(state, argv + 1, REJECT_EMPTY_ADDR, SLOPPY) != 0) {
@@ -3501,8 +3561,10 @@ static int etrn_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
 	argv[1].strval++;
 
     /*
-     * As an extension to RFC 1985 we also allow an RFC 2821 address literal
-     * enclosed in [].
+     * As an extension to RFC 1985 we also allow an RFC 2821 address
+     * literal enclosed in []. Note that RFC6531 extends the syntax to
+     * allow UTF8 in the argument, but forbids clients from using UTF8
+     * in EHLO, so we call valid_hostname().
      */
     if (!valid_hostname(argv[1].strval, DONT_GRIPE)
 	&& !valid_mailhost_literal(argv[1].strval, DONT_GRIPE)) {
@@ -3673,7 +3735,7 @@ static int xclient_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
 	    if (name_status != SMTPD_PEER_CODE_OK) {
 		attr_value = CLIENT_NAME_UNKNOWN;
 	    } else {
-		if (!valid_hostname(attr_value, DONT_GRIPE)) {
+		if (!valid_mail_domain(attr_value, DONT_GRIPE)) {
 		    state->error_mask |= MAIL_ERROR_PROTOCOL;
 		    smtpd_chat_reply(state, "501 5.5.4 Bad %s syntax: %s",
 				     XCLIENT_NAME, attr_value);
@@ -3698,7 +3760,7 @@ static int xclient_cmd(SMTPD_STATE *state, int argc, SMTPD_TOKEN *argv)
 	    if (name_status != SMTPD_PEER_CODE_OK) {
 		attr_value = CLIENT_NAME_UNKNOWN;
 	    } else {
-		if (!valid_hostname(attr_value, DONT_GRIPE)) {
+		if (!valid_mail_domain(attr_value, DONT_GRIPE)) {
 		    state->error_mask |= MAIL_ERROR_PROTOCOL;
 		    smtpd_chat_reply(state, "501 5.5.4 Bad %s syntax: %s",
 				     XCLIENT_REVERSE_NAME, attr_value);
@@ -4671,6 +4733,9 @@ static void smtpd_proto(SMTPD_STATE *state)
 	|| (ehlo_words = maps_find(ehlo_discard_maps, state->addr, 0)) == 0)
 	    ehlo_words = var_smtpd_ehlo_dis_words;
 	state->ehlo_discard_mask = ehlo_mask(ehlo_words);
+#ifdef NO_EAI
+	state->ehlo_discard_mask |= EHLO_MASK_SMTPUTF8;
+#endif
 
 	/* XXX We use the real client for connect access control. */
 	if (SMTPD_STAND_ALONE(state) == 0
diff --git a/src/smtpd/smtpd.h b/src/smtpd/smtpd.h
index 8bd1176..40af759 100644
--- a/src/smtpd/smtpd.h
+++ b/src/smtpd/smtpd.h
@@ -190,6 +190,7 @@ typedef struct {
 #define SMTPD_FLAG_HANGUP	   (1<<0)	/* 421/521 disconnect */
 #define SMTPD_FLAG_ILL_PIPELINING  (1<<1)	/* inappropriate pipelining */
 #define SMTPD_FLAG_AUTH_USED	   (1<<2)	/* don't reuse SASL state */
+#define SMTPD_FLAG_SMTPUTF8	   (1<<3)	/* message uses RFC 6531/2 */
 
  /* Security: don't reset SMTPD_FLAG_AUTH_USED. */
 #define SMTPD_MASK_MAIL_KEEP		~0	/* keep all after MAIL reset */
diff --git a/src/smtpd/smtpd_check.c b/src/smtpd/smtpd_check.c
index 79175ee..3408d74 100644
--- a/src/smtpd/smtpd_check.c
+++ b/src/smtpd/smtpd_check.c
@@ -1174,7 +1174,7 @@ static int reject_invalid_hostname(SMTPD_STATE *state, char *name,
     /*
      * Validate the hostname.
      */
-    if (!valid_hostname(test_name, DONT_GRIPE)
+    if (!valid_mail_domain(test_name, DONT_GRIPE)
 	&& !valid_hostaddr(test_name, DONT_GRIPE))	/* XXX back compat */
 	stat = smtpd_check_reject(state, MAIL_ERROR_POLICY,
 				  var_bad_name_code, "5.5.2",
@@ -1212,7 +1212,7 @@ static int reject_non_fqdn_hostname(SMTPD_STATE *state, char *name,
     /*
      * Validate the hostname.
      */
-    if (!valid_hostname(test_name, DONT_GRIPE) || !strchr(test_name, '.'))
+    if (!valid_mail_domain(test_name, DONT_GRIPE) || !strchr(test_name, '.'))
 	stat = smtpd_check_reject(state, MAIL_ERROR_POLICY,
 				  var_non_fqdn_code, "5.5.2",
 			 "<%s>: %s rejected: need fully-qualified hostname",
@@ -1837,7 +1837,9 @@ static int reject_non_fqdn_address(SMTPD_STATE *state, char *addr,
     /*
      * Validate the domain.
      */
-    if (!*test_dom || !valid_hostname(test_dom, DONT_GRIPE) || !strchr(test_dom, '.'))
+    if (!*test_dom ||
+	!valid_mail_domain(test_dom, DONT_GRIPE) ||
+	!strchr(test_dom, '.'))
 	stat = smtpd_check_reject(state, MAIL_ERROR_POLICY,
 				  var_non_fqdn_code, "4.5.2",
 			  "<%s>: %s rejected: need fully-qualified address",
@@ -3382,7 +3384,7 @@ static const SMTPD_RBL_STATE *find_dnsxl_domain(SMTPD_STATE *state,
      * the name has an alphanumerical prefix. We play safe, and skip both
      * RHSBL and RHSWL queries for names ending in a numerical suffix.
      */
-    if (domain[0] == 0 || valid_hostname(domain, DONT_GRIPE) == 0)
+    if (domain[0] == 0 || valid_mail_domain(domain, DONT_GRIPE) == 0)
 	return (SMTPD_CHECK_DUNNO);
     suffix = strrchr(domain, '.');
     if (alldig(suffix == 0 ? domain : suffix + 1))
diff --git a/src/trivial-rewrite/resolve.c b/src/trivial-rewrite/resolve.c
index d9a709e..a0855c3 100644
--- a/src/trivial-rewrite/resolve.c
+++ b/src/trivial-rewrite/resolve.c
@@ -382,7 +382,7 @@ static void resolve_addr(RES_CONTEXT *rp, char *sender, char *addr,
     if (*rcpt_domain == '[') {
 	if (!valid_mailhost_literal(rcpt_domain, DONT_GRIPE))
 	    *flags |= RESOLVE_FLAG_ERROR;
-    } else if (!valid_hostname(rcpt_domain, DONT_GRIPE)) {
+    } else if (!valid_mail_domain(rcpt_domain, DONT_GRIPE)) {
 	if (var_resolve_num_dom && valid_hostaddr(rcpt_domain, DONT_GRIPE)) {
 	    vstring_insert(nextrcpt, rcpt_domain - STR(nextrcpt), "[", 1);
 	    vstring_strcat(nextrcpt, "]");
diff --git a/src/util/Makefile.in b/src/util/Makefile.in
index 5ab2232..6813de5 100644
--- a/src/util/Makefile.in
+++ b/src/util/Makefile.in
@@ -27,7 +27,7 @@ SRCS	= alldig.c allprint.c argv.c argv_split.c attr_clnt.c attr_print0.c \
 	sys_compat.c timed_connect.c timed_read.c timed_wait.c timed_write.c \
 	translit.c trimblanks.c unescape.c unix_connect.c unix_listen.c \
 	unix_recv_fd.c unix_send_fd.c unix_trigger.c unsafe.c uppercase.c \
-	username.c valid_hostname.c vbuf.c vbuf_print.c vstream.c \
+	username.c uses_utf_8.c valid_hostname.c vbuf.c vbuf_print.c vstream.c \
 	vstream_popen.c vstring.c vstring_vstream.c watchdog.c \
 	write_buf.c sane_basename.c format_tv.c allspace.c \
 	allascii.c load_file.c killme_after.c vstream_tweak.c \
@@ -65,7 +65,7 @@ OBJS	= alldig.o allprint.o argv.o argv_split.o attr_clnt.o attr_print0.o \
 	sys_compat.o timed_connect.o timed_read.o timed_wait.o timed_write.o \
 	translit.o trimblanks.o unescape.o unix_connect.o unix_listen.o \
 	unix_recv_fd.o unix_send_fd.o unix_trigger.o unsafe.o uppercase.o \
-	username.o valid_hostname.o vbuf.o vbuf_print.o vstream.o \
+	username.o uses_utf_8.o valid_hostname.o vbuf.o vbuf_print.o vstream.o \
 	vstream_popen.o vstring.o vstring_vstream.o watchdog.o \
 	write_buf.o sane_basename.o format_tv.o allspace.o \
 	allascii.o load_file.o killme_after.o vstream_tweak.o \
diff --git a/src/util/host_port.c b/src/util/host_port.c
index 644d8b7..e5c6eee 100644
--- a/src/util/host_port.c
+++ b/src/util/host_port.c
@@ -154,7 +154,7 @@ const char *host_port(char *buf, char **host, char *def_host,
      * Final sanity checks. We're still sloppy, allowing bare numerical
      * network addresses instead of requiring proper [ipaddress] forms.
      */
-    if (*host != def_host && !valid_hostname(*host, DONT_GRIPE)
+    if (*host != def_host && !valid_mail_domain(*host, DONT_GRIPE)
 	&& !valid_hostaddr(*host, DONT_GRIPE))
 	return ("valid hostname or network address required");
     if (*port != def_service && ISDIGIT(**port) && !alldig(*port))
diff --git a/src/util/printable.c b/src/util/printable.c
index 9e27f94..8ea875b 100644
--- a/src/util/printable.c
+++ b/src/util/printable.c
@@ -41,11 +41,22 @@
 
 char   *printable(char *string, int replacement)
 {
-    char   *cp;
+    unsigned char *cp;
     int     ch;
 
-    for (cp = string; (ch = *(unsigned char *) cp) != 0; cp++)
-	if (!ISASCII(ch) || !ISPRINT(ch))
+    cp = (unsigned char *)string;
+    while((ch = *cp) != 0) {
+	if (ISASCII(ch) && ISPRINT(ch)) {
+	    // ok
+	} else if (ch >= 194 && ch <= 254 && cp[1] >= 128 && cp[1] < 192) {
+	    // UTF8; skip the rest of the bytes in the character
+	    while (cp[1] >= 128 && cp[1] < 192)
+		cp++;
+	} else {
+	    // defintely not ok - switch to replacement
 	    *cp = replacement;
+	}
+	cp++;
+    }
     return (string);
 }
diff --git a/src/util/stringops.h b/src/util/stringops.h
index 85d2a74..b347779 100644
--- a/src/util/stringops.h
+++ b/src/util/stringops.h
@@ -42,6 +42,7 @@ extern int allspace(const char *);
 extern int allascii(const char *);
 extern const char *split_nameval(char *, char **, char **);
 extern int valid_utf_8(const char *, ssize_t);
+extern int uses_utf_8(const char *);
 
 /* LICENSE
 /* .ad
diff --git a/src/util/uses_utf_8.c b/src/util/uses_utf_8.c
new file mode 100644
index 0000000..cbb801b
--- /dev/null
+++ b/src/util/uses_utf_8.c
@@ -0,0 +1,51 @@
+/*++
+/* NAME
+/*	uses_utf_8 3
+/* SUMMARY
+/*	predicate if string is UTF-8
+/* SYNOPSIS
+/*	#include <stringops.h>
+/*
+/*	int	uses_utf_8(str, len)
+/*	const char *str;
+/*	ssize_t	len;
+/* DESCRIPTION
+/*	uses_utf_8() determines if a string contains at least one byte
+/*	with the high bit set. It does not actually verify that the string
+/*	is valid UTF-8, merely that where UTF-8 is treated differently from
+/*	ASCII, the UTF-8 path must be taken.
+/*
+/*	A zero-length string is considered to be ASCII.
+/* DIAGNOSTICS
+/*	The result value is zero when the caller specifies an empty string
+/*	or one that contains only bytes in the range 0-127, and one if
+/*	at least one byte is in the range 128-255.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+
+/* Utility library. */
+
+#include <stringops.h>
+
+/* uses_utf_8 - check whether a string needs UTF-8 treatment. */
+
+int     uses_utf_8(const char *str)
+{
+    const unsigned char * cp = (const unsigned char *)str;
+    while (cp && *cp)
+	if (*cp++ > 128)
+	    return 1;
+    return 0;
+}
diff --git a/src/util/valid_hostname.c b/src/util/valid_hostname.c
index 7a40d6e..9790f90 100644
--- a/src/util/valid_hostname.c
+++ b/src/util/valid_hostname.c
@@ -162,6 +162,118 @@ int     valid_hostname(const char *name, int gripe)
     return (1);
 }
 
+
+/* valid_mail_domain - screen out obviously bad mail domains.
+
+   With RFC6531 support, hostnames are no longer equal to the
+   right-hand side of an email address. The precise rules for what
+   constitudes a valid right-hand side are complex; 0xC0 0x80 is
+   always illegal (being an overlong UTF8 form), but 0xC0 0xB0 may or
+   may be legal, depending on the rules of the TLD registry.
+
+   This function is somewhat robust, but not enough that
+   e.g. valid_rr_name() ought to call it.
+ */
+
+int     valid_mail_domain(const char *name, int gripe)
+{
+    const char *myname = "valid_mail_domain";
+    const unsigned char *cp;
+    int     label_length = 0;
+    int     label_count = 0;
+    int     non_numeric = 0;
+    int     ch;
+    
+    /*
+     * Trivial cases first.
+     */
+    if (*name == 0) {
+	if (gripe)
+	    msg_warn("%s: empty hostname", myname);
+	return (0);
+    }
+
+    /*
+     * Find bad characters or label lengths. Find adjacent delimiters.
+     */
+    cp = name;
+    while ((ch = *cp) != 0) {
+	if (ISALNUM(ch) || ch == '_' || (ch >= 194 && ch < 254)) {
+	    if (label_length == 0)
+		label_count++;
+	    label_length++;
+	    if (label_length > VALID_LABEL_LEN) {
+		if (gripe)
+		    msg_warn("%s: hostname label too long: %.100s", myname, name);
+		return (0);
+	    }
+	    if (!ISDIGIT(ch))
+		non_numeric = 1;
+	    if (ch >= 194) {
+		/* UTF8 consists of one byte >= 194 and then one or
+		   more in the range 128-191. Bytes 192 and 193 are
+		   only used by nogoodniks (192,128 is an illegal way
+		   to encode a null character) and I think it's best
+		   to deny them: There are no MTAs that generate that
+		   and with which we need to be compatible.
+
+		   There are many ways to play games with UTF8 and
+		   Unicode that we cannot possible detect here, so
+		   we'll just test that the sequence looks vaguely
+		   plausible and leave the rest to ICU
+		   (see callers of uidna_labelToASCII_UTF8()).
+		*/
+		while (cp[1] >= 128 && cp[1] < 192)
+		    cp++;
+	    }
+	} else if (ch == '.') {
+	    if (label_length == 0 || cp[1] == 0) {
+		if (gripe)
+		    msg_warn("%s: misplaced delimiter: %.100s", myname, name);
+		return (0);
+	    }
+	    label_length = 0;
+	} else if (ch == '-') {
+	    non_numeric = 1;
+	    label_length++;
+	    if (label_length == 1 || cp[1] == 0 || cp[1] == '.') {
+		if (gripe)
+		    msg_warn("%s: misplaced hyphen: %.100s", myname, name);
+		return (0);
+	    }
+	}
+#ifdef SLOPPY_VALID_HOSTNAME
+	else if (ch == ':' && valid_ipv6_hostaddr(name, DONT_GRIPE)) {
+	    non_numeric = 0;
+	    break;
+	}
+#endif
+	else {
+	    if (gripe)
+		msg_warn("%s: invalid character %d(decimal): %.100s",
+			 myname, ch, name);
+	    return (0);
+	}
+	cp++;
+    }
+
+    if (non_numeric == 0) {
+	if (gripe)
+	    msg_warn("%s: numeric hostname: %.100s", myname, name);
+#ifndef SLOPPY_VALID_HOSTNAME
+	return (0);
+#endif
+    }
+    if ((const char *)cp - name > VALID_HOSTNAME_LEN) {
+	if (gripe)
+	    msg_warn("%s: bad length %d for %.100s...",
+		     myname, (int) ((const char *)cp - name), name);
+	return (0);
+    }
+    return (1);
+}
+
+
 /* valid_hostaddr - verify numerical address syntax */
 
 int     valid_hostaddr(const char *addr, int gripe)
diff --git a/src/util/valid_hostname.h b/src/util/valid_hostname.h
index b06fc17..7b8465f 100644
--- a/src/util/valid_hostname.h
+++ b/src/util/valid_hostname.h
@@ -24,6 +24,7 @@ extern int valid_hostaddr(const char *, int);
 extern int valid_ipv4_hostaddr(const char *, int);
 extern int valid_ipv6_hostaddr(const char *, int);
 extern int valid_hostport(const char *, int);
+extern int valid_mail_domain(const char *, int);
 
 /* LICENSE
 /* .ad