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Subject: sending mail to a not permanent online top MX record designated server
From: Arjen Runsink (arjentechnologist.com)
Date: Wed May 10 2000 - 08:19:53 CDT

L.S.

The following behaviour of postfix is seen using my private home machine
running postfix and that of some other company sending mail to domain
with following MX records in the DNS.

            foobar.com. 0S IN MX 50
mail.foobar.com.
            foobar.com. 0S IN MX 75
backup1.foo2.net.
            foobar.com. 0S IN MX 100
backup2.foo2.net.

mail.foobar.com is dial-out only. When online mail is received directly,
if not offline mail is retrieved every 15 minutes or so from backup1. by
using ETRN.

Situation:
system mail.foobar.com is off-line

Action:
user sends email to someone at foobar.com

Observed:
Postfix resolves DNS and tries to reach mail.foobar.com but is
unsuccessful and 'holds it'. The message is queued but, using 'sendmail
-q' or 'postfix flush' it is not resent / retried. After about 2 hours
the message is sent to backup1.foo2.net

Problem:
Mail delivery to this machine (and maybe others) from my private
dial-on-demand-not-always-on system is hampered. Mail sent from other
companies that use Postfix is delayed conciderable. Often the messages
contain operational data for which a 15 minute delay is no problem, but
a 2 hour or more is.

Question:
Is there a rationale for this behaviour? Can this behaviour be altered
by some (not so) obscure setting?

TIA.

BB, Arjen 

--
Sell what you use, use what you sell.