Log Message:
Changes 2.2.9:
+ Full text search indexing can now be done automatically after
  saving/copying mails by setting plugin { fts_autoindex=yes }
+ replicator: Added replication_dsync_parameters setting to pass
  "doveadm sync" parameters (for controlling what to replicate).
+ Added mail-filter plugin
+ Added liblzma/xz support (zlib_save=xz)
- v2.2.8's improved cache file handling exposed several old bugs
  related to fetching mail headers.
- v2.2.7's iostream handling changes were causing some connections
  to be disconnected before flushing their output (e.g. POP3 logout
  message wasn't being sent)