Hi,

We have mail server in production, with Exim + Dovecot + Mailman + OpenLDAP + Roundcube webmail server.
Openldap keeps mail accounts in db, exim uses lmtp transport to deliver messages to dovecot.
Mailman is responsible for mailing lists, Roundcube webmail has managsieve module to create sieve filters.

Exim router,transport for dovecot
localuser:
  driver = accept
  domains = +local_domains : +virt_domains
  check_local_user
  transport = dovecot_lmtp
  cannot_route_message = Unknown account
  no_more
 
dovecot_lmtp:
  driver = lmtp
  socket = /var/spool/dovecot/lmtp
  batch_max = 500
  rcpt_include_affixes

It worked perfectly, but after upgrade from Dovecot 2.2 to Dovecot 2.3 major version, I've found a lot of strange errors in exim panic.log
mail exim[7821]  Failed to get user name for uid 1175
mail exim[7880]: Failed to get user name for uid 1173
etc
where uids are ldap accounts and recognized by system (id 1175 shows user's name and group)

Even worse, some clients start to receive notify email with strange content, when sending email to mailing lists
 user@domain.com
    Delay reason: error in redirect data: malformed address:
    someuser1@domain.com may not follow someuser2@domain.com  in "someuser3@domain.com ..some crap here.." , where someuser addresses are not related to recipient address and unknown for sender.

After some investigation,I've found out that dovecot's sieve produces these errors (I suspect sieve vacation, when user creates vacation via Roundcube webmail).
If set "submission_host = exim ip" in dovecot.conf, exim doesn't produce errors in panic.log anymore, but clients still receive email with malformed address.
Please help me to find the root of the problem (some broken sieve filter in user's maildir, misconfiguration or breaking changes in new Dovecot version?)

Current software
Gentoo  with 4.14.90 kernel
Dovecot-2.3.7.1
Exim-4.92.1
Mailman 2.1.29
Openldap-2.4.47
Roundcube-1.3.8

Dovecot.conf attached

Regards,
Juri