Procmail Module Library is a collection of many plug-in modules for the Procmail mail processing utility. The modules allow common tasks like parsing dates, times, MIME, and email addresses, forwarding mail, dealing with POP3, spam shielding, running email cron jobs, handling daemon messages, and more.
OpenVISP Admin is a fork of Postfix Admin. Its aim is to provide a unique ISP tool as a Web panel for end users, postmasters, and site administrator to manage their data. It allows site administrators to update amavisd-new values, spam-assassin values, greylisting, domains checks, and sender verification. It can also provide datacenter admins with a central point of access, by having APC Masterswitch configuration and access, hosting access requests, and PPTP access and statistics views.
msmtp is an SMTP client with a sendmail compatible interface. It can be used with Mutt and other MUAs. It forwards messages to an SMTP server which does the delivery. Features include various SMTP AUTH methods, TLS/SSL-encrypted connections (including support for client certificates), support for multiple accounts, DSN, and IPv6 support.
Tagspam is suitable for situations where it is not possible for tagging to be done at the MTA receiving all mail for a domain (e.g., in virtual hosting situations, where it is only possible to tag and filter spam after this point). Tagspam makes use of DNSBL black and whitelists and may be installed to tag and thereby help filter mail for a single Linux or Unix user.
CRM114 is a generalized filter. It is useful for spam filtering, syslog monitoring, and other common tasks. CRM114 is a mutating filter based on regex matching, and it can call and be called by shell scripts and commands. When used as a spam filter, it can achieve over 99.9% accuracy.