diff -U4 -r exim-4.66/src/acl.c exim-4.66+data-accept-message/src/acl.c
--- exim-4.66/src/acl.c	2007-01-08 14:25:36.000000000 +0000
+++ exim-4.66+data-accept-message/src/acl.c	2007-02-11 11:16:38.000000000 +0000
@@ -3075,10 +3075,10 @@
   However, the value of an existing message is available in $acl_verify_message
   during expansions. */
 
   if (verb == ACL_WARN ||
-      (rc == OK && (verb == ACL_ACCEPT || verb == ACL_DISCARD)))
-    *log_msgptr = *user_msgptr = NULL;
+      (rc == OK && (verb == ACL_ACCEPT || verb == ACL_DISCARD || verb == ACL_REQUIRE)))
+    if (verb == ACL_WARN) *log_msgptr = *user_msgptr = NULL;
 
   if (user_message != NULL)
     {
     acl_verify_message = old_user_msgptr;
@@ -3089,8 +3089,9 @@
         log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand ACL message \"%s\": %s",
           user_message, expand_string_message);
       }
     else if (expmessage[0] != 0) *user_msgptr = expmessage;
+    else *user_msgptr = NULL;
     }
 
   if (log_message != NULL)
     {
@@ -3264,8 +3265,9 @@
 int fd = -1;
 acl_block *acl = NULL;
 uschar *acl_name = US"inline ACL";
 uschar *ss;
+BOOL require_message = FALSE;
 
 /* Catch configuration loops */
 
 if (level > 20)
@@ -3386,9 +3388,11 @@
   int cond;
   int basic_errno = 0;
   BOOL endpass_seen = FALSE;
 
-  *log_msgptr = *user_msgptr = NULL;
+  *log_msgptr = NULL;
+  /* If a "require" verb returned a message (only set when processing a DATA ACL), don't reset it. */
+  if (!require_message) *user_msgptr = NULL;
   acl_temp_details = FALSE;
 
   if (where == ACL_WHERE_QUIT &&
       acl->verb != ACL_ACCEPT &&
@@ -3497,8 +3501,10 @@
     break;
 
     case ACL_REQUIRE:
     if (cond != OK) return cond;
+    /* If this is a DATA ACL, the message needs to be preserved. */
+    if (where == ACL_WHERE_DATA) require_message = (*user_msgptr != NULL ? TRUE : FALSE);
     break;
 
     case ACL_WARN:
     if (cond == OK)
@@ -3524,8 +3530,9 @@
 
 /* We have reached the end of the ACL. This is an implicit DENY. */
 
 HDEBUG(D_acl) debug_printf("end of %s: implicit DENY\n", acl_name);
+if (require_message) *user_msgptr = NULL;
 return FAIL;
 }