[Dovecot] lmtp sometimes fails to deliver a message to all recipients

[Artur Zaprzała]

Dovecot version: 2.1.3

lmtp config:
protocol lmtp {
   mail_plugins = zlib acl sieve
}

Running strace on lmtp reveals that when lmtp delivers a message to multiple 
recipients it saves the message to a file in the first mailbox and hard links 
that file to other mailboxes. But when in the meantime of delivery that file is 
deleted, lmtp fails to deliver the message to remaining mailboxes. For example a 
message for 46 recipients is delivered by lmtp to the first 12 only (fortunately 
postfix retries delivery for remaining recipients) and for the rest lmtp logs 
the following error messages:

lmtp(3344, foo at domain): Error: RU1WMnueeU9QDQABxjIODQ: sieve: msgid=unspecified: 
failed to store into mailbox 'INBOX': Message was expunged (guid)
lmtp(3344, foo at domain): Error: RU1WMnueeU9QDQABxjIODQ: sieve: script 
/vmail/domain/foo/.dovecot.sieve failed with unsuccessful implicit keep (user 
logfile /vmail/domain/foo/.dovecot.sieve.log may reveal additional details)

I'm seeing this error for about 10 messages per hour.


Best regards,
Artur Zaprzała