Walter Pelissero wrote some interesting Common Lisp software:
- A native implementation of the Milter protocol
- A(nother) Lisp SMTP server
- CLPMR, the Common Lisp ProcMail Replacement
- BINGE, the Bovine INterface GEnerator for Common Lisp
- ASDF extensions
- MArch, a Mail Archiver
- ...
