[Howto] solve “lost connection with [private/dovecot-lmtp] while sending end of data”-error

if you use postfix and dovecot via LMTP you can get the following error messages:

#postfix.log
status=deferred (lost connection with <xxxxxxxxx> [private/dovecot-lmtp] while sending end of data -- message may be sent more than once

#dovecot.log
Fatal: master: service(lmtp): child 76549 returned error 83 (Out of memory (service lmtp { vsz_limit=256 MB }, you may need to increase it) - set CORE_OUTOFMEM=1 environment to get core dump)

problem: the message-size is too big to deliver via LMTP from postfix to dovecot. The connection is closed before the complete message is transfered.

solution: increase the vsz_limit parameter in dovecot.conf

#dovecot.conf
service lmtp {
      vsz_limit = 512 MB
}

reflush the postfix mail-queue to deliver the message again with the command postfix flush.

Now the message should be delivered (check your logfiles).