MIMEDefang is a flexible MIME email scanner designed to do all kinds of email processing, including anti-virus scanning, anti-spam scanning, replacing parts of messages with URLs, adding boilerplate disclaimers, and so on. It can alter or delete various parts of a MIME message according to a Perl-based policy filter. It can also bounce messages with unacceptable attachments and modify SMTP response codes on the fly. It works with the Sendmail 8.11 and newer "Milter" API, which makes it more flexible and efficient than procmail-based approaches.
Sylpheed is a simple, lightweight but featureful, and easy-to-use email client. It has a well-polished and comfortable user interface. It has many features such as multiple accounts, thread display, MIME, powerful filtering, various search interface, spell checking, and junk mail control. It supports common email protocols such as POP3, IMAP4rev1, SMTP, and security features such as GnuPG and SSL/TLSv1. It is also fully internationalized and multilingualized.
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.
The DBMAIL package replaces the normal UNIX mailing system. All email and user data is stored in a database. You can create an unlimited number of email accounts, which can be checked using the POP3 or IMAP protocol. Users can maintain their own set of email addresses. It is more scalable, more secure, and faster than traditional mail systems. DBMAIL has storage drivers for PostgreSQL and MySQL, and it has authentication drivers for PostgreSQL, MySQL, and LDAP.
Mutt is a small but very powerful text-based MIME mail client. It is highly configurable, and is well-suited to the mail power user with advanced features like key bindings, keyboard macros, mail threading, regular expression searches, and a powerful pattern matching language for selecting groups of messages.
Postgrey is a Postfix policy server that implements greylisting. When a request for mail delivery is received by Postfix via SMTP, the triplet CLIENT_IP / SENDER / RECIPIENT is built. If it is the first time that this triplet is seen, or if the triplet was first seen less than 10 minutes ago, then the mail gets rejected with a temporary error. Hopefully, spammers or viruses will not try again later, even though such behavior is required per RFC.
DocumentBurster is a tool for report distribution: split, merge, email, and FTP your reports. It has report delivery for Crystal Reports, SSRS Reporting Services, MS Access, Cognos, PeopleSoft, and SAP. It has report bursting for Pentaho, JasperReports, and BIRT. It can upload reports to MS SharePoint.
Xplico is an IP traffic decoder that extracts data from an Internet traffic capture. From a pcap file, it can extracts each email (POP, IMAP, and SMTP protocols), all HTTP content, VoIP calls (SIP, RTP, H323, MEGACO, MGCP), IRC, MSN, and so on. It isn't a packet sniffer or a network protocol analyzer, but rather an IP/Internet traffic decoder or network forensic analysis tool (NFAT).
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.