Log Message:
Update to dovecot-1.0rc23.  From the release announcement mail:

Documentation is probably the only important thing left before v1.0.

	* deliver doesn't ever exit with Dovecot's internal exit codes anymore.
	  All its internal exit codes are changed to EX_TEMPFAIL.
	* mbox: X-Delivery-ID header is now dropped when saving mails.
	* mbox: If pop3_uidl_format=%m, we generate a unique X-Delivery-ID
	  header when saving mails to make sure the UIDL is unique.

	+ PAM: blocking=yes in args uses an alternative way to do PAM checks.
	  Try it if you're having problems with PAM.
	+ userdb passwd: blocking=yes in args makes the userdb lookups be done
	  in auth worker processes. Set it if you're doing remote NSS lookups
	  (eg. nss_ldap problems are fixed by this).
	+ If PAM child process hasn't responded in two minutes, send KILL
	  signal to it (only with blocking=no)
	- IMAP: APPEND ate all CPU while waiting for more data from the client
	  (broken in rc22)
	- mbox: Broken X-UID headers assert-crashed sometimes
	- mbox: When saving a message to an empty mbox file it got an UID
	  which immediately got incremented.
	- mbox: Fixed some wrong "uid-last unexpectedly lost" errors.
	- auth cache: In some situations we crashed if passdb had extra_fields.
	- auth cache: Special extra_fields weren't saved to auth cache.
	  For example allow_nets restrictions were ignored for cached entries.
	- A lot of initial login processes could cause auth socket errors
	  in log file at startup, if dovecot-auth started slowly. Now the
	  login processes are started only after dovecot-auth has finished
	  initializing itself.
	- imap/pop3 proxy: Don't crash if the remote server disconnects before
	  we're logged in.
	- deliver: Don't bother trying to save the mail twice into the default
	  mailbox (eg. if it's over quota).
	- mmap_disable=yes + non-Linux was really slow with large
	  dovecot.index.cache files
	- MySQL couldn't be used as a masterdb
	- Trash plugin was more or less broken
	- imap/pop3 couldn't load plugins if they chrooted
	- imap/pop3-login process could crash in some conditions
	- checkpassword-reply crashed if USER/HOME wasn't set