Univention Corporate Server 4.2 erratum 12 (bugfix)

This update addresses the following issue(s):
* After an upgrade from UCS 4.1 to UCS 4.2 the Cyrus daemons did not
  start automatically anymore. When installing this bugfix the service
  will be enabled automatically in systemd (Bug #44377).
* The paths to Cyrus executables have been adjusted for Debian Jessie
  (Bug #44424, Bug #44566).
* The path to the tool to automatically purge old entries from the Cyrus
  "duplicate delivery database" has been fixed. As the path was wrong in
  the past, the tool never ran. When starting it (the first time), it may
  take minutes or hours (depending on the database size). Thus for this
  update the tool has been disabled by default, but it will be enabled
  by default when updating to UCS 4.2-1. Via the new UCR variables
  mail/cyrus/duplicate-supression/expiry/start and
  mail/cyrus/duplicate-supression/expiry/event this cleanup job can be
  configured to be run when starting Cyrus or regularly at 4:01 each
  night (Bug #22852).