Broaden your selection:
- Abook is a text-based addressbook program specifically designed to use with mutt mail client (although it can also be used independently). It has import filters for mutt, pine, and the Netscape addressbook, and export filters for mutt, pine, the Netscape addressbook, HTML, elm, plain text, spruce, and the GnomeCard addressbook.
- 'acmemail' is a multiuser IMAP/POP3 to Web gateway (or webmail program). It reads mail from a mail server and displays it using HTML on a web server. It has full support for MIME and mod_perl and is quite pretty.
- Alpine is a screen-oriented message-handling tool. In its default configuration, Alpine offers an intentionally limited set of functions geared toward the novice user, but it also has a large list of optional "power-user" and personal-preference features. alpinef is a variant of Alpine that uses function keys rather than mnemonic single-letter commands. Alpine uses the c-client messaging API to access local and remote mail folders. This library provides a variety of low-level message-handling functions, including drivers for a variety of different mail file formats, as well as routines to access remote mail and news servers, using IMAP (Internet Message Access Protocol) and NNTP (Network News Transport Protocol). Outgoing mail is usually posted directly via SMTP (Simple Mail Transfer Protocol).
- Althea is an IMAP E-Mail client for Gtk. Supports such advanced features as multiple servers, IMAP over SSL and message filtering.
- Anguly Mail Client
- A lightweight Mail Client written in C and Gtk+, with Pop3, Imap, GMail, Smtp Support, currently support only Pop3 and SMTP.
- Animail is a multiserver POP3/APOP/IMAP4 (with or without SSL) mail retrieval utility. It has an advanced filtering system based on blacklisting, whitelisting, or a combination of both, and can send an autoresponse which prompts people to reply and add themselves to the 'autoaccept' file. It also allows filters based on regular expressions which match against email headers. (If a message is filtered, only the header is downloaded, not the entire body.) users can also combine external filtering programs (e.g. SpamAssassin or Bogofilter) as message post-download plugins, which extends filtering capabilities in an unlimited way. Delivery options include mailbox, maildir, local SMTP, and pipe to a command.
- Astroid is a lightweight and fast Mail User Agent that provides a graphical interface to searching, display and composing email, organized in thread and tags. Astorid uses the notmuch backend for blazingly fast searches through tons of email. Astroid searches, displays and compose emails - and rely on other programs for fetching, syncing and sending email. Check out Astroid in your general mail setup for a suggested complete mail solution. 
- BAD HARVEST
- BAD HARVEST is a form-mail CGI script designed to be called from links similar to "mailto:...". It helps you to hide email addresses from "harvesters" (automated email-address collectors) while still providing a convenient way for your visitors to contact you.