Prereq: "3.4.9"
diff -ur --new-file /var/tmp/postfix-3.4.9/src/global/mail_version.h ./src/global/mail_version.h
--- /var/tmp/postfix-3.4.9/src/global/mail_version.h	2020-02-02 15:13:52.000000000 -0500
+++ ./src/global/mail_version.h	2020-03-12 10:52:04.000000000 -0400
@@ -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	"20200203"
-#define MAIL_VERSION_NUMBER	"3.4.9"
+#define MAIL_RELEASE_DATE	"20200312"
+#define MAIL_VERSION_NUMBER	"3.4.10"
 
 #ifdef SNAPSHOT
 #define MAIL_VERSION_DATE	"-" MAIL_RELEASE_DATE
diff -ur --new-file /var/tmp/postfix-3.4.9/HISTORY ./HISTORY
--- /var/tmp/postfix-3.4.9/HISTORY	2020-02-02 12:51:46.000000000 -0500
+++ ./HISTORY	2020-03-12 10:58:26.000000000 -0400
@@ -24339,3 +24339,10 @@
 	macros were evaluated before the Milter connection itself
 	had been negotiated. Problem reported by David Bürgin.
 	Files: milter/milter.h, milter/milter.c, milter/milter8.c
+
+20200312
+
+	Bugfix (introduced: Postfix 2.3): panic with Postfix
+	multi-Milter configuration during MAIL FROM. Milter client
+	state was not properly reset after one of the Milters failed.
+	Reported by WeiYu Wu.
diff -ur --new-file /var/tmp/postfix-3.4.9/src/smtpd/smtpd.c ./src/smtpd/smtpd.c
--- /var/tmp/postfix-3.4.9/src/smtpd/smtpd.c	2019-06-29 09:33:39.000000000 -0400
+++ ./src/smtpd/smtpd.c	2020-03-12 10:43:18.000000000 -0400
@@ -2605,6 +2605,7 @@
     }
     if (state->milters != 0
 	&& (state->saved_flags & MILTER_SKIP_FLAGS) == 0) {
+	state->flags |= SMTPD_FLAG_NEED_MILTER_ABORT;
 	PUSH_STRING(saved_sender, state->sender, STR(state->addr_buf));
 	err = milter_mail_event(state->milters,
 				milter_argv(state, argc - 2, argv + 2));
@@ -2720,11 +2721,14 @@
 	state->queue_id = 0;
     }
     if (state->sender) {
-	if (state->milters != 0)
-	    milter_abort(state->milters);
 	myfree(state->sender);
 	state->sender = 0;
     }
+    /* WeiYu Wu: need to undo milter_mail_event() state change. */
+    if (state->flags & SMTPD_FLAG_NEED_MILTER_ABORT) {
+	milter_abort(state->milters);
+	state->flags &= ~SMTPD_FLAG_NEED_MILTER_ABORT;
+    }
     if (state->verp_delims) {
 	myfree(state->verp_delims);
 	state->verp_delims = 0;
diff -ur --new-file /var/tmp/postfix-3.4.9/src/smtpd/smtpd.h ./src/smtpd/smtpd.h
--- /var/tmp/postfix-3.4.9/src/smtpd/smtpd.h	2018-08-23 08:51:53.000000000 -0400
+++ ./src/smtpd/smtpd.h	2020-03-12 10:43:18.000000000 -0400
@@ -206,6 +206,7 @@
 #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)	/* RFC 6531/2 transaction */
+#define SMTPD_FLAG_NEED_MILTER_ABORT (1<<4)	/* undo milter_mail_event() */
 
  /* Security: don't reset SMTPD_FLAG_AUTH_USED. */
 #define SMTPD_MASK_MAIL_KEEP \