[Kolab-devel] [issue4785] kolabmailboxfilter produces temporary failure for nonexistent recipient

[Sascha Wilde]

When an mail for an nonexistent recipient enters the Kolab Server
(which is for example possible by creating an invalid local name in
the virtual table) the kolabmailboxfilter signals an temporary
failure.

>From the postfix log:
Sep 22 11:45:44 cipactli <info> postfix/pipe[17967]: E69DF411AE00:
to=<non-existent at example.com>, relay=kolabmailboxfilter, delay=436,
delays=436/0.06/0/0.18, dsn=4.3.0, status=deferred (temporary failure)

>From /kolab/var/kolab-filter/log/filter.log:
Sep 22 11:45:44 Kolab Filter (pid=17968) [error] [horde] Specify either the UID
or a search result!; Code: 331 [pid 17968 on line 181 of
"/kolab/lib/php/Horde/Kolab/Server/Object.php"]

This is wrong as the failure is by nature permanent, the mail should
be bounced immediately.  I'm not quiet sure what the correct solution
would be (as I don't know what the deeper semantics of the "Specify
either the UID or a search result!" error are):

- kolabmailboxfilter could generate a fatal error and trigger the
  bounce -- but is it really kolab-filter's duty to generate an error
  in this situation?

- kolabmailboxfilter could be more tolerant and pass the mail on, so
  that LMTP would create the bounce.

To reproduce:

1. Add an entry for an nonexistent local destination in
   /kolab/etc/kolab/templates/virtual.template
   e.g.:
     jibbetnich      non-existent

2. run /kolab/sbin/kolabconf

3. send an Mail to the new virtual address:
   jibbetnich at example.com


Background:

This issue is not only relevant for faulty virtual entries.  We are
using entries of the form:
  @example.net    @example.com
so that the same set of addresses (more precisely local parts) exist
in both domains.  Unfortunately postfix reject_unlisted_recipient does
not work for the virtual domain, so while non-existent at example.com is
rejected non-existent at example.net is not and triggers the problem at
hand.

A serious problem comes from this issue when many mails are send to
such an invalid address (e.g. SPAM or misconstrued services): as every
mail is held in the queue for long the mailqueue fills up pretty fast.

----------
assignedto: wrobel
keyword: filter, server
messages: 28247
nosy: martin, thomas, wickert, wilde, wrobel
priority: bug
status: unread
title: kolabmailboxfilter produces temporary failure for nonexistent recipient

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Kolab issue tracker <issues at kolab.org>
<https://issues.kolab.org/issue4785>
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