Free smtp server software for linux

Dwarf Mail Server is a full-featured mail server developed on the Java platform, implementing SMTP, POP3 and IMAP4rev1 protocols.
Dwarf Mail Server provides support for rich application message processing via pluggable mail filters and agents, as well as full handling of virtual domains for the SMTP/POP3/IMAP4 protocols, and is free of charge for the binary redistribution.
Since the server is based on the Dwarf framework, it also shares its common design principles and features - simplicity, high modularity and extensibility, authentication and authorization, XML-based configuration, logging and remote management.
Main features:
- ESMTP, POP3 and IMAP4rev1 implementation
- application logic layer provided by mail filters and agents
- virtual mail hosts in SMTP/POP3/IMAP4 server
- application-independent authentication and authorization
- sample JSP-based webmail interface
Dwarf Mail Server is targeted for both end users who are just looking for simple, secure and robust mail server as well as developers who need an extensible and powerful framework for application message processing.
For users with minimal requirements it can offer portability, simple configuration as well as strong security.
- Portability: several OS platforms are supported via the Java technology, including MS Windows, UNIX/Linux/BSD, MacOS X and others.
- Configuration: just 3 lines have to be changed to fire up a sample mail server and a few of them to run a full featured SMTP/POP3/IMAP4 server.
- Security: it uses Java Platform Security Architecture in combination with Java Authentication and Authorization Service (JAAS), as well as SSL/TLS for the secure communication.
Advanced or enterprise users can additionally appreciate performance scalability, multiple domain handling, enhanced security features and modular design easing to incorporate it to the existing infrastructure.
- Scalability: gaining from multithreaded design and dynamically adjustable allocation of resources.
- Multiple domains: server is able to handle multiple virtual domains in a single instance for all SMTP, POP and IMAP protocols.
- Enhanced security: includes subject-based permissions and access control lists for IMAP, SMTP relaying control rules, host-based filtering, SSL/TLS communication, basic anti-spam filtering, etc.
- Robustness: client/server network communication is by design separated from the resource-expensive application logic layer. The server implementation is based on the unparsed byte streams whenever possible, including its own and highly efficient MIME parser.
Dwarf Mail Server also appears to be a suitable platform for application development and customization. Its modular structure and lightweight API allows enhancing existing functionality or completely exchanging the certain part as a whole:
- Message processing: mail filters and agents provide an unique infrastructure for rich message processing.
- Mail queue: physical mail queue representation is abstracted by the API specification and may replaced by a custom implementation.
- Storage subsystem: physical data representation (i.e. messages, folders, configuration options, ACLs) is abstracted by API and may be replaced by a custom implementation based on filesystem, SQL database, etc.
- MIME parser: the parsing engine may be reimplemented for the top efficiency according to the currently used mail storage.
Dwarf Mail Sever has been tested with the most popular mail clients like MS Outlook, Mozilla, Thunderbird, Opera, Apple Mail, Becky!, Pegasus, Eudora, Pine, The Bat! and others.
Other features:
- multi-threaded server
- dynamically adjusted number of active threads
- server API for mail, user data and ACL storages
- robust SMTP server architecture with flexible queue design
- simultaneous deliveries to remote SMTP hosts
- transparent Delivery System Notification (DSN) mechanism
- support for shared mail folders
- fast and universal stream-oriented MIME parser
- runtime server configuration
- built-in SSL/TLS support
- full documentation with user guides and tutorials
- samples with source code

SMTPHandler is a handler for the java.util.logging library. SMTPHandler sends LogRecords via email using the Simple Mail Transfer Protocol.
The SMTPHandler code is derived from log4js SMTPAppender.
After downloading the SMTPHandler software, you will need to download two additional JAR files:
1) Sun JavaMail
http://java.sun.com/products/javamail
2) Sun JavaBeans Activiation Framework
http://java.sun.com/products/javabeans/glasgow/jaf.html
Enhancements:
- This release adds SMTP server authentication.
- You can specify an SMTP username and SMTP password.