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Re: smtp_fallback_relay ignored

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  • Noel Jones
    ... The smtp_fallback_relay is used when relayhost cannot be reached. In this case, a server was contacted at the relayhost IP, and that server rejected the
    Message 1 of 3 , Nov 9, 2011
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      On 11/9/2011 6:19 AM, Christian Vieser wrote:
      > Hi,
      >
      > we have a two ISP setup and each ISP provides us with an mail relay
      > accessible within their networks.
      > So we have in our postfix configurations
      > relayhost = [relaying.ISP1.com]
      > smtp_fallback_relay = [relaying.ISP2.com]
      > to provide some fault tolerance. This works pretty good in case we
      > have problems with one of our ISPs.
      >
      > Yesterday ISP1 changed the IP address of his relay. Therefore the
      > routing rules on the firewall didn't match any more and the packets
      > went down the wrong way. Consequently they were rejected by the relay:
      >
      > Nov 9 08:56:03 mailhost postfix/pickup[14967]: 4D0373A2C7: uid=104
      > from=<XY>
      > Nov 9 08:56:03 mailhost postfix/cleanup[15247]: 4D0373A2C7:
      > message-id=<20111109075603.4D0373A2C7@mailhost>
      > Nov 9 08:56:03 mailhost postfix/qmgr[1496]: 4D0373A2C7:
      > from=<XY@...>, size=1072, nrcpt=1 (queue active)
      > Nov 9 08:56:03 mailhost postfix/smtp[15249]: 4D0373A2C7:
      > to=<XYZ@...>, orig_to=<XYZ>,
      > relay=relaying.ISP1.com[aa.bbb.ccc.ddd]:25, delay=0.14,
      > delays=0.03/0.01/0.07/0.03, dsn=5.7.1, status=bounced (host
      > relaying.ISP1.com[aa.bbb.ccc.ddd] said: 554 5.7.1
      > <XYZ@...>: Relay access denied (in reply to RCPT TO command))
      > Nov 9 08:56:03 mailhost postfix/bounce[15250]: 4D0373A2C7: sender
      > non-delivery notification: 70A193A2C8
      > Nov 9 08:56:03 mailhost postfix/qmgr[1496]: 4D0373A2C7: removed
      >
      > So, first question is: why doesn't postfix try to deliver the mails
      > through the fallback relay?

      The smtp_fallback_relay is used when relayhost cannot be reached.
      In this case, a server was contacted at the relayhost IP, and that
      server rejected the mail.
      http://www.postfix.org/postconf.5.html#smtp_fallback_relay

      > Second question: Even if I had no fallback relay defined, I wouldn't
      > like the mails to be discarded as happened here.

      The mail was not discarded, rather it was returned to the sender.

      > Is there a way I
      > can instruct postfix to keep the mails in his queue (at least to
      > maximal_queue_lifetime ), so that they can be delivered when the
      > problem is solved?

      You might add "-o soft_bounce=yes" to the master.cf smtp...smtp
      transport entry (NOT in main.cf). Be aware that setting soft_bounce
      can cause other problems and is not recommended other than for testing.
      http://www.postfix.org/postconf.5.html#soft_bounce



      -- Noel Jones
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