Fix qmail-remote to handle multiple MX records correctly as in rfc2821

This patch changes qmail-remote to skip over MX servers that greet with
codes 400 to 499 and to bounce mail when any MX server that qmail tries
greets with a code 500 to 599.

see http://www-dt.e-technik.uni-dortmund.de/~ma/qmail/patch-qmail-1.03-rfc2821.diff

1 files changed, 3 insertions, 2 deletions

diff --git a/qmail-remote.c b/qmail-remote.c
index be997f0..dc00d08 100644
--- a/qmail-remote.c
+++ b/qmail-remote.c
@@ -569,7 +569,8 @@ void smtp()
 #endif
  
   code = smtpcode();
-  if (code >= 500) quit("DConnected to "," but greeting failed");
+  if (code >= 500 && code < 600) quit("DConnected to "," but greeting failed");
+  if (code >= 400 && code < 500) return; /* try next MX, see RFC-2821 */
   if (code != 220) quit("ZConnected to "," but greeting failed");
  
 #ifdef EHLO
@@ -948,7 +949,7 @@ char **argv;
 #ifdef TLS
       partner_fqdn = ip.ix[i].fqdn;
 #endif
-      smtp(); /* does not return */
+      smtp(); /* only returns when the next MX is to be tried */
     }
     tcpto_err(&ip.ix[i].ip,errno == error_timeout);
     close(smtpfd);