MH-sync is a small suite of command-line tools designed to allow an MH user to read mail offline by synchronizing a local set of MH folders with the "real" MH folders online at a remote site. Changes made using 'rmm' and 'refile' will be propagated back to the server site correctly without being affected by "folder -pack" or server-side message filing or removal. ssh is used as the transport, and no other ports need be open on the firewall.
MIMEDefang is a flexible MIME email scanner designed to do all kinds of email processing, including anti-virus scanning, anti-spam scanning, replacing parts of messages with URLs, adding boilerplate disclaimers, and so on. It can alter or delete various parts of a MIME message according to a Perl-based policy filter. It can also bounce messages with unacceptable attachments and modify SMTP response codes on the fly. It works with the Sendmail 8.11 and newer "Milter" API, which makes it more flexible and efficient than procmail-based approaches.
Minimalist is a mailing list manager. It is small, fast, and easy to setup and maintain. It supports per-user settings, a write-only subscription option, multiple languages, a workaround for MIME-encoded messages, several levels of security, archiving, blacklisting, and more. It can be configured on a per-list basis as well as globally.