Log Message:
Changes 2.2.7:
* Some usage of passdb checkpassword could have been exploitable by
  local users. You may need to modify your setup to keep it working.
  See http://wiki2.dovecot.org/AuthDatabase/CheckPassword#Security
+ auth: Added ability to truncate values logged by
  auth_verbose_passwords (see 10-logging.conf comment)
+ mdbox: Added "mdbox_deleted" storage, which can be used to access
  messages with refcount=0. For example: doveadm import
  mdbox_deleted:~/mdbox "" mailbox inbox subject oops
+ ssl-params: Added ssl_dh_parameters_length setting.
- master process was doing a hostname.domain lookup for each created
  process, which may have caused a lot of unnecessary DNS lookups.
- dsync: Syncing over 100 messages at once caused problems in some
  situations, causing messages to get new UIDs.
- fts-solr: Different Solr hosts for different users didn't work.