MailSteward will archive all of your email in a database for easy retrieval, without touching or modifying the email in your email client program. Just click on the Store Email in Database button and MailSteward will go to work storing copies of all your email, both text and HTML versions, and attachments, into a relational database file. You can then retrieve email and attachments from the database by searching on Date, From, To, Subject, Mailbox, or Body text.
The SeaMonkey project is a community effort to develop an all-in-one Internet application suite. It contains an Internet browser, email and newsgroup client with an included Web feed reader, HTML editor, IRC chat, and Web development tools, and is sure to appeal to advanced users, Web developers, and corporate users. It uses much of the Mozilla source code powering such successful siblings as Firefox, Thunderbird, Camino, Sunbird, and Miro.
Cerb is a fast and flexible Web-based platform for business collaboration and automation. It helps you remember anything about anyone, collaborate from anywhere, deftly reply to a flood of email, automate, stay informed, capture feedback, track time, flag opportunities, manage tasks, share expert knowledge, and otherwise execute efficiently.
Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
tkbiff allows arbitrary commands to be executed upon mail reception. If you like programs such as xbiff and xbiff++ but wish they were more flexible, then you'll like tkbiff. Unlike other biffs, tkbiff is fully customizable. tkbiff also doesn't waste your valuable screen space with icons; instead, it shows you the mail itself. It supports UNIX, Mac, and Windows, IMAP, POP, and UNIX-style mail files, and SSL and APOP.
ADJE WebMail is a set of Perl CGI scripts which provide a Web interface to existing email accounts on any POP3-compliant email server. The software provides a complete interface, including encoding/decoding attachments, email and URL markup in received emails, and an address book for each user.
PHP Mobile Mail is aimed at mobile professionals who want to use their favorite MUAs (noteably pine or mutt) on their laptop, either in UNIX or Windows (under GNU Gygwin). This lets you work offline. It includes a mail_spooler program, which accepts the output of you MUA and spools (on, or offline). When connected, another process parses through the spool and sends your messages. It is also designed to "fake" using your REAL email address with free services like gmx.net, or mail.yahoo.com, when using their POP and SMTP servers, assuming you have a domain and account that you can control to this degree.
yaspi (Yosi's Anti-Spam POP3 fIlter bot) is a POP3 mail-scanner specifically made to combat mail bombings caused by viruses (i.e. Swen). It connects to the POP3 server, inspects the messages, and deletes the infected ones without ever downloading them. Its most interesting feature is that it can automatically send abuse reports to the ISPs from which the infected mails originated.
getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.