VCF2alias is a tool to extract name and email information from VCF attachments (automatically if you use the enclosed mailcap), and writes a line (user-defined) to a file (user-defined). Originally, VCF2alias was aimed at mutt, but it should now work with any mail program that has text-file alias definitions.
listadmin is a command-line alternative to Mailman's Web interface for administering mailing lists. It allows you to inspect messages or subscription requests, approve or discard them manually, or discard messages automatically when certain conditions are true. listadmin can also be configured to run out of cron to do routine cleaning.
minimap (minimalistic IMAP) is a non-compliant dummy IMAP server to allow a user to subscribe to the server and drag mail items from another server into either INBOX or "Junk E-mail", which are the only two (fake) mailboxes supported. The intention is for the APPEND command to be used to upload spam and ham in order for a Bayesian mailer such as spamprobe to have a feedback mechanism for retraining. This is for sites where the spam filtering is being done on-the-fly with an SMTP filter before the email gets to the final delivery system. This dummy IMAP server would therefore run on the filter box. It is a suitable companion program for the smtpfilter project.
smtpfilter is a filter for an SMTP session which passes the session through transparently in real time, except for the DATA command which is intercepted in order to scan the data for spam and/or viruses with the scanner of your choice. The sources are heavily commented. The default spam filtering is a hybrid approach that uses spamassassin to self-train the excellent spamprobe Bayesian filter which works on a per-site rather than per-user basis. The virus checking can use clamav or NAI, or any other command- line scanner.