Log Message:
Update to 0.55. Changes:

* Tighter integration of the local delivery code.  An external LDA
  like procmail is now required only if you are running Sendmail.
  Further, if you are driving TMDA with procmail, you no longer need
  to maintain a second procmailrc (e.g, ~/.procmailrc-tmda) for final
  delivery.

* Improvements to the mailing list filter file sources.

* Bugfixes.