Atmail is a fully-featured email server and Webmail client, allowing users to send and receive email via a Web browser or mobile device. It has full support for IMAP mailboxes, and an optional email-server mode that uses EXIM as the MTA. Features include a scheduler, MySQL backend support, spell-check, address book, calendar user preferences, multiple accounts, SpamAssassin support, migration scripts from other mail servers, a customizable interface, an attractive AJAX interface, an optional group sharing Calendar/Addressbook, and an Outlook plugin to sync Contacts/Tasks/Calendar data between a Desktop, Mobile, and Webmail client or other email users.
Scandalo is a very efficient and fast mail frontend for the clamdscan virus scanner. In other words, it is a simple mail filter that works as a wrapper for clamd, the famous Clamav antivirus daemon. Once integrated in maildrop or any MTA or MUA, it can quickly read messages and send them to the clamd process for virus scanning using the clamdscan utility. When a virus is found, the message is marked with a header, so you can easily set up your mail filter or MUA to drop, quarantine, or move the infected message to a mail folder.
Melon MailServer is a simple mail server emulator for developers. It can emulate POP3 and SMTP services. The SMTP facility receives and stores all the messages sent to it rather than sending them. The POP3 facility allows you to download any messages without authorization. The server is designed to accept all messages for any email accounts. It can be very useful for testing Web applications and other software applications.
CleanMail is a complete SMTP/POP3 email security solution that fights against spam and viruses. It works with any mail server like Microsoft Exchange 2003/2007/2010, Microsoft Small Business Server (SBS) 2003/2008, Lotus Notes/Domino, or IMail. CleanMail includes a comprehensive set of filters, including an attachment blocker, remote blacklist filter (DNSBL), and a complete build of SpamAssassin.
Rumble is a mail server suite for SMTP (ESMTPSA), HTTP, POP3, and IMAP4v1 with an extensive C/C++ and Lua API for scripting. It comes with support for SSL/TLS, SQLite, and MySQL and has a Web-based administration and Web mail feature. Additional included modules feature greylisting, DNS blacklisting, SpamAssassin support, and dynamic performance scaling as well as a multithreaded structure that allows for clustering of multiple servers for one or all domains. With the Lua API you can create your own new server mailing lists, CRM software, e-marketing, and other extensions within minutes.