Mireka is a mail server with SMTP, Mail Submission, and POP3 services. It can also be used as an SMTP proxy. As a proxy, it can help to prevent or diagnose mail problems, like outgoing backscatter spam. It provides detailed logging, basic mail traffic statistics, tarpit to prevent email harvesting, and loop detection. It can filter email by DNSBL, SPF, mail size, local domains, and recipients list. Local recipients can be specified using regular expressions. TLS is supported for incoming connections. Aliases, forward lists, and very simple mailing lists can be configured in XML. Custom filters and other components can be written in Java, and they can be easily implemented and installed.
SubEthaSMTP is an easy to understand Java library that provides a receptive SMTP server component. By plugging this component into your Java application, you can easily receive SMTP mail using a simple abstract Java interface. Also included is a small sub-project called Wiser, an easy to use incoming mail testing framework.
Dove is an application that facilitates the distribution of documents to a variety of destination types such as email, local files, FTP, FTPS, SFTP, TFTP, Samba servers, Windows network shared drives, and WebDAV servers. Being an abstraction layer over previously enumerated protocols, it allows sending of documents to email or to a WebDAV server with equal ease.
Apache SpamAssassin is an extensible email filter that is used to identify spam. Once identified, the mail can then be optionally tagged as spam for later filtering. It provides a command line tool to perform filtering, a client-server system to filter large volumes of mail, and Mail::SpamAssassin, a set of Perl modules allowing Apache SpamAssassin to be used in a wide variety of email systems.
FuzzyOcr is a plugin for SpamAssassin that can be used on image spam. It supports optical character recognition using different engines and settings, a fuzzy word matching algorithm applied to OCR results, an image hashing system to learn the unique properties of known spam images, dimension, size, and integrity checking of images, and content-type verification for the containing email message.
The deepOfix Mail Server makes it possible for organizations with minimal technical expertise to have robust server infrastructure. deepOfix offers unprecented ease of use, doesn't require prior GNU/Linux experience and is backed by a full-time development and support team. deepOfix features LDAP-based directory services for user account management, email delivery, distribution lists, and addressbooks. It also includes built in tools for spam and virus control, webmail, and fetching email.
GreenMail is a suite of email servers for testing purposes and sandbox development. It supports SMTP, POP3, and IMAP (including SSL) and can be embedded into any Java application or unit test. The GreenMail Service (SAR) extension runs as a JBoss embedded developer mail server sandbox, manageable via JMX.
Chandler is a standards-based "Note-to-Self Organizer" designed for personal and small-group task management and calendaring. It consists of a desktop application and Chandler Hub, a free sharing service and Web application. You can also download and run your own Chandler Server.