- Mailgraph, an RRDTool front-end for Postfix statistics
- ytnef - TNEF stream reader.
- tnef - another.
- MIMEDefang, for processing MIME attachments (and other stuff).
- mbox-uniq - remove dupes from mailbox files.
- Laird Breyer's mail tools, which include a generic Bayesian classifier (i.e., it does more than just filter out junk mail):
