--- qmail-remote.c	2007-06-01 04:13:53.000000000 -0500
+++ qmail-remote.c	2007-06-01 21:42:36.000000000 -0500
@@ -564,7 +564,10 @@
   if (!smtps)
 #endif
  
-  if (smtpcode() != 220) quit("ZConnected to "," but greeting failed");
+  code = smtpcode();
+  if (code >= 500 && code < 600) return; /* try next MX per RFC-2821 */
+  if (code >= 400 && code < 500) return; /* try next MX per RFC-2821 */
+  if (code != 220) quit("ZConnected to "," but greeting failed");
  
 #ifdef EHLO
 # ifdef TLS
@@ -591,7 +594,11 @@
   substdio_put(&smtpto,helohost.s,helohost.len);
   substdio_puts(&smtpto,"\r\n");
   substdio_flush(&smtpto);
-  if (smtpcode() != 250) quit("ZConnected to "," but my name was rejected");
+  
+  code = smtpcode();
+  if (code >= 500 && code < 600) return; /* try next MX per RFC-2821 */
+  if (code >= 400 && code < 500) return; /* try next MX per RFC-2821 */
+  if (code != 250) quit("ZConnected to "," but my name was rejected");
  
 #ifdef EHLO
   }
@@ -638,8 +645,8 @@
     mail_without_auth();
   }
   code = smtpcode();
-  if (code >= 500) quit("DConnected to "," but sender was rejected");
-  if (code >= 400) quit("ZConnected to "," but sender was rejected");
+  if (code >= 500 && code < 600) return; /* try next MX per RFC-2821 */
+  if (code >= 400 && code < 500) return; /* try next MX per RFC-2821 */
  
   flagbother = 0;
   for (i = 0;i < reciplist.len;++i) {
@@ -668,7 +675,7 @@
       flagbother = 1;
     }
   }
-  if (!flagbother) quit("DGiving up on ","");
+  if (!flagbother) return; /* try next MX per RFC-2821 */
  
   substdio_putsflush(&smtpto,"DATA\r\n");
   code = smtpcode();
@@ -843,7 +850,7 @@
 #ifdef TLS
       partner_fqdn = ip.ix[i].fqdn;
 #endif
-      smtp(); /* does not return */
+      smtp(); /* Returns on 400-599 error so next MX will be checked */
     }
     tcpto_err(&ip.ix[i].ip,errno == error_timeout);
     close(smtpfd);