MDaemon   
http://www.altn.com

MDaemon , Windows-based email server software, contains full mail server functionality and control with a strong emphasis on security to protect your email communication needs. MDaemon features include top-notch antispam security features; seamless integration with AntiVirus for MDaemon plug-in; built-in groupware functionalities for sharing folders, tasks, contacts, and address; separately licensed plug-in for Outlook users to access groupware functionalities using MDaemon as the mail server and groupware platform; secure instant messaging; free web-based email client; remote administration tool; central address book repository; and much more! MDaemon 8.1 new feature includes the first implementation of DomainKeys Identified Mail (DKIM) for the Microsoft Windows platform. DKIM validates the sender address and message integrity of each email received. MDaemon creates outbound signatures and validates inbound messages signed with DKIM. Read Alt-N's published white paper on DKIM and its implementation in MDaemon at http://www.altn.com/support/white_papers.asp. In addition to DKIM, MDaemon 8.1 includes support for Greylisting, a relatively new spam fighting technique which involves deferring the initial acceptance of a new mail message from unknown senders and tells the sending email server to try again later. When the sending server tries a second time - which most spam sources will not do - MDaemon will accept it. Exception options and white lists can exempt trusted senders from greylist processing. MDaemon 8.1 builds on the groupware, security and administrative improvements made available with MDaemon 8.0. MDaemon now includes free groupware functions, including shared calendars, contacts and task lists. It also continues to lead the industry in email security, professional fine-tuning and beginner ease of use.

Merak Mail Server Suite   
http://www.icewarp.com

Multiple awards winner mail server with ultimate features, complete security and guaranteed stability. Provides a wide range of optional components and services including secured mail services with multiple domain support(SMTP, POP3, IMAP), user-friendly Web-Mail (Outlook-like interface), Anti-Spam with updates (SpamAssassin, SPF, Bayes, SURBL, ChallengeResponse, DomainKeys, Greylisting), Anti-Virus with updates, Instant Messaging (based on the Jabber XMPP protocol, also accessiale via web, supporting AOL, ICQ, MSN, Yahoo and other Jabber and Merak servers), GroupWare (accessible via web and Outlook), FTP (secure FTP server with many features and the system integration), load balancing (ODBC support), monitoring and report facilities (charts and reports), developers API, several account types (mailing lists, list servers, executables, catalogs, static routes, remote accounts, users, domains), system alert tools, remote administration and many other features and tools. Merak mail server suite is a reliable, easy to use, and affordable communication solution that is used by more than 40 million users worldwide. Available on Windows and Unix based systems.

Aloaha SPAM rejector   
http://www.aloaha.com

Innovative server based AntiSPAM Solution. Incl. Sender Policy Framework and Sender ID Support! Does not depend on IIS or Exchange. Works together with every SMTP Server. Mail archiving, Remote Black-/Whitelists, relaxed greylisting, script engine and lots of other features. Does not accept spam. Rejects spam before reaching the SMTP Server. Now also with POP3 Interface (downloader) and SINK Plugin! .