Deferred messages, cyrus is the cause?

[Andreas Haase]

Hello,

I have a strange problem on my mail server running sendmail 8.12.10 and
Cyrus 2.1.15. Most of the time all messages are delivered to the user
accounts. But sometimes a message gets status "Deferred" without a
clear reason in the log files.

--- snip ---
Jul 21 12:37:41 mail sendmail-tx[5789]: i6LAbe7U005779:
   to=<localpart1 at domain>, delay=00:00:01,
   xdelay=00:00:00, mailer=cyrusv2, pri=121960, relay=localhost,
   dsn=2.0.0, stat=Sent
Jul 21 12:37:41 mail sendmail-tx[5809]: i6LAbf7U005794:
   to=<localpart2 at domain>, delay=00:00:00, xdelay=00:00:00,
   mailer=cyrusv2, pri=127881, relay=localhost, dsn=4.2.0, stat=Deferred
Jul 21 12:37:41 mail sendmail-tx[5807]: i6LAbf7U005791:
   to=<localpart3 at domain>, delay=00:00:00, xdelay=00:00:00,
   mailer=cyrusv2, pri=162479, relay=localhost, dsn=2.0.0, stat=Sent
--- snap ---

So all 3 delivery attempts took place in the same second, two of them were
successful, one message got deferred with DSN 4.2.0. All 3 addresses exist
on the the server. If I try to deliver the message in question by

--- snip ---
sendmail -C/etc/sendmail-tx.cf -qIi6LAbf7U005794 -v
--- snap ---

it goes through as I want. So can anybody give me a hint why some messages
can't be delivered first but then cause no error when delivering manually?
Other errors aren't displayed in the logfile. Does it help if I increase
the debug level? If yes, how do I do that?

Thanks in advance,
Andreas
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