Python SRS Library is a Python translation of the Perl reference implementation for SRS (Sender Rewriting Scheme) with easy to install packaging and built-in sendmail integration. SRS is needed when forwarding mail for SMTP authorization schemes that publish which IPs are authorized to send mail from a domain (for example SPF - Sender Policy Framework). It can also detect forged SMTP bounces by signing the return path for outgoing mail.
PMilter implements Sendmail's "milter" mail filtering protocol in Perl, allowing scripts direct access to the SMTP transaction in progress, rather than filtering later. It can function as a drop-in replacement for Sendmail::Milter, though PMilter does not require threads or the "libmilter" API to be available.
FetchYahoo is a Perl script that downloads mail from a Yahoo! account to a local mail spool. It is meant to replace fetchmail for people using Yahoo! mail since Yahoo!'s POP service is no longer free. It downloads messages to a local mail spool, including all parts and attachments. It then deletes messages unless requested not to. It can also optionally forward messages to a specified email address and repeat with a given interval.
vthrottle is an implementation of an SMTP throttling engine for Sendmail servers, based upon M. Williamson's mechanisms, as described in his 2003 Usenix Security paper. It allows the administrator to control how much email users and hosts may send, hindering the rapid spread of viruses, worms, and spam. Exceptions can be made using a whitelist mechanism, which can be generated manually or with the included tool "vmeasure". vthrottle tells the misbehaving client to hold on to the deferred mail and resend it at a later time.
pb.WebMAUI (Web-Mail Administration User Interface) is a Web-based administration tool for managing complex mail domains, mail user accounts, server-based filtering including "out-of-office mail replies", and mail-related tasks. User quota managment is supported as well. Currently, the Courier mail suite is used, but support for other MTAs is planned.