parp is a powerful, extensible e-mail filter with sophisticated anti-spam capabilities. It's designed as a complete replacement for procmail, is MIME-aware, and acts as a filter, daemon, or on mailboxes. It uses the Open Relay Database as part of its spam-detection heuristics, and it has a DBM-format database of trusted e-mail addresses to ensure that false positives are kept to a minimum. It can perform duplicate removal by message ID, and has many other features.
Perdition is a fully featured POP3 and IMAP4 proxy server. It is able to handle both SSL and non-SSL connections and redirect users to a real-server based on a database lookup. Perdition supports modular based database access. The distribution ships with modules for ODBC, MySQL, PostgreSQL, GDBM, POSIX Regular Expression, and NIS. The API for modules is open, allowing abitary modules to be written to allow access to any data store. Perdition can be used to create large mail systems where an end-user's mailbox may be stored on one of several hosts, to integrate different mail systems together, to migrate between different email infrastructures, and to bridge plain-text, SSL, and TLS services. It can also be used as part of a firewall.
Perl Webmail is a CGI/mod_perl application that interfaces with external POP3 and SMTP services. It provides all the expected functionality of a mail client, such as read, reply, forward, delete, as well as sending and receiving attachments, storage for mail folders, contacts, and calendar notes.
pflogsumm.pl is designed to provide an over-view of postfix activity, with just enough detail to give the administrator a "heads up" for potential trouble spots. Reports includes: Total number of messages and bytes; Hosts/Domains; senders and Recipients; per-hour traffic reports; summaries of warnings, fatal errors, and panics; and so on ...
phpGroupWare (formerly known as webdistro) is a multi-user groupware suite written in PHP. Its provides a Web-based calendar, todo-list, addressbook, email, news headlines, and a file manager. The calendar supports repeating events. The email system supports inline graphics and file attachments. The system as a whole supports user preferences, themes, user permissions, multi-language support, an advanced API, and user groups.
phplist is a mailing list and newsletter manager that allows posting via a Web page. It works well when used for announcements, and can handle very large email address lists. Users can sign up to multiple lists, but will only receive a single copy of cross-posted messages. When signing up, users can identify their geographical location, and messages can be targetted to these. You can add place holders in your email that will be replaced with personal details (such as the person's name). Users can update their own information, and unlike many other mailing list systems, they can change their email address. HTML emails are supported.