GroupWare 

MDaemon GroupWare unlocks the collaborative functions of Microsoft Outlook using MDaemon as the mail server platform. Outlook users can share Calendar, Tasks, Contacts, Notes, and Journal folders without the expense or expertise required by Exchange.
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CoffeeCup Spam Blocker 

Spam Blocker works with any POP3 email account. It checks your HTML and Text email and removes spam right from the mail server so you never see it in your regular inbox. Spam Blocker automatically Removes Attached Viruses and more.
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RelayTest 

RelayTest Pro is a tool for network administrators, that allows to test a specified mail server for open relays. It runs series of tests designed to detect open relays and create a detailed report of the findings.
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BusinessMail Email Server + Anti Spam System 

Fully multi threaded email server and anti-spam system with POP/SMTP plus web interface, offering powerful fully asynchronous operations, fully user configurable anti-spam system, user configurable filtering, aliasing, list handling plus lots more.
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Smart Email Verifier 

Smart Email Verifier will check every email address from a given mailing list and determine if e-mails are still valid. It does 3 levels of checking; e-mail syntax, existence of SMTP mail server and e-mail box on server.
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Out Spam 

Out Spam is a spam filter program. It can remove junk letters from a POP3 mail server without downloading them to a client computer. The principal way to separate mail is the use of worldwide black lists of spam mail servers.
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