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@domain): Error: RU1WMnueeU9QDQABxjIODQ: sieve: msgid=unspecified: failed to store into mailbox 'INBOX': Message was expunged (guid) lmtp(3344, foo@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