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Abook 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 '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 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 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 '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.

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.

BFilter BFilter is a smart filtering HTTP proxy. It removes ads, webbugs, and popups. Unlike the majority of similar tools, it doesn't rely on a list of blocked URLs, but instead parses HTML on the fly, and detects ads using a set of heuristic rules. BFilter has a built-in JavaScript engine which detects popups and js-generated ads.

Balsa Balsa is a Gnome e-mail client supporting mbox, maildir, and mh local mailboxes, and POP3, IMAP4 remote mailboxes. It can be compiled with multi-threading support for faster response, and can do nifty things like read your GnomeCard address book, use LDAP, and render HTML mail.

Batemail 'batemail' is a script that goes between your MTA (e.g. Sendmail) and your local mailer (e.g. Procmail) to strip potentially nasty attachments from email messages. It takes input on STDIN, removes executable MIME attachments, and gives the result to the local mailer. Taboo attachments are those whose filename ends in one of several "blacklisted" extensions (EXE, VBS, etc.).

Black Hole Blackhole stops spam and prevents unwanted senders from sending you email. It is put in the .qmail file and will divert spam and viruses to separate files which can be checked with an IMAP client if configured to do so. It not only uses the RBL type servers, but also checks against your own list of good/bad domains/users. You can also block email that is sent to an address that is not specified in a list of addresses to use for emailing you. Blackhole can log and keep the email it blocks, and can be configured to either reply with a message of your choice or make it look like you don't exist on the system. You can also add relays to the list of relays that the script skips. It also has subject line checking with ^ and $ matching lines, and includes a virus checking server program.

Blq 'blq' is a script that queries various databases that list known spammers one to determine if a particular host is listed.

Bogofilter Bogofilter is a Bayesian spam filter. It takes an email message or other text on standard input, does a statistical check against lists of "good" and "bad" words, and returns a status code indicating whether or not the message is spam. It is designed with fast algorithms (including Berkeley DB system), and tuned for speed, so it can be used for production by sites that process a lot of mail.

CRM114 'CRM114' is a Controllable Regex Mutilator and Smart Filter, designed for easy creation of filters for things like incoming email redirection, spam filtering, system logs, or monitoring processes. Filtering rules can be either hard-coded (such as regexes), soft-coded (calculated at runtime or read from an external file or process), or learned dynamically by phrase matching (by SBPH hashing). This makes it possible to create very accurate filters over (99.9%) with very little actual work.

Cats2procmailrc cats2procmailrc is a filter to generate a .procmailrc file from a much terser file consisting of single-line rules. These suffice to do the most common mail filing, making maintenance of a procmailrc very easy for someone with more than a few filing rules. Each rule basically names the folder, an optional subject tag, and the pattern.

Claws Mail Claws Mail is an email client (and news reader), based on GTK+, featuring * Quick response

• Graceful, and sophisticated interface
  
• Easy configuration, intuitive operation
  
• Abundant features
  
• Extensibility
  
• Robustness and stability
  

The appearance and interface are designed to be familiar to new users coming from other popular email clients, as well as experienced users. Almost all commands are accessible with the keyboard. The messages are managed in the standard MH format, which features fast access and data security. You'll be able to import your emails from almost any other email client, and export them just as easily.

Cone Cone (COnsole Newsreader And Emailer) is a text-based email client. It seamlessly handles multiple POP3 and IMAP accounts and local mail folders. It is also a simple newsreader. It is designed to be foolproof enough to be used by inexperienced users, but also offers advanced features for power users.

Contact Form 'Contact Form' lets users send you email through a Web interface. It thwarts spammers by not allowing email to be sent to unknown addresses, and by not revealing the addresses that it knows. Additionally, it does not contain cross site scripting vulnerabilities or allow arbitrary code to be run on the host. It provides adequate information in the headers it sends to trace spammers, can check the validity of all data before sending emails, and has a customizable interface that allows arbitrary fields.

Courier The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open commodity protocols such as ESMTP, IMAP, POP3, LDAP, SSL, and HTTP. It provides ESMTP, IMAP, POP3, webmail, and mailing list services within a single, consistent, framework. Individual components can be enabled or disabled at will. Courier now implements basic web-based calendaring and scheduling services integrated in the webmail module. Courier implements SMTP extensions for mailing list management and spam filtering. Courier can function as an intermediate mail relay, relaying mail between an internal LAN and the Internet, or perform final delivery to mailboxes. Courier uses maildirs as its native mail storage format, but it can also deliver mail to legacy mailbox files as well. Courier's configuration is set by plain text files and Perl scripts. Most of Courier's configuration can now be adjusted from a web browser, using Courier's web-based administration module.

Courier-IMAP Courier-IMAP is a lightweight server that provides IMAP access to maildir mailboxes. It supports folders, custom authentication modules, and virtual mailboxes. A compatible POP3 server is also provided. The source code is based on the IMAP module in the Courier Mail Server, but this build is independently repackaged to work with any other MTA that delivers to maildir format mailboxes.