Mail servers are used to transfer electronic messages over computer network. Mails are transfered with SMTP.

SMTP is the name given to the protocol (or langauge) that is used to transfer email messages between computers. The language has only ten or so words to reduce bandwidth and improve performance. SMTP stands for "Simple Mail Transport Protocol".

Most modern mail servers use ESMTP. ESMTP, stands for "Enhanced Simple Mail Transport Protocol" adds many enhancements to the SMTP protocol. These include security, authentication and other devices designed to save bandwidth and protect servers.

Popular Mail Servers

Following are some of the popular open source email server for unix, linux and freebsd servers.

• Exim - MTA used in Cpanel Servers.
• Postfix - Default MTA of ubentu linux, is versy secure and efficient, easy to configure.
• Qmail - used in Plesk servers.
• Sendmail - Default MTA used by many of the linux distro.

Mail Servers for Windows are

• MS SMTP - Free with Windows by Microsoft
• MailEnable - is a high perfomance POP3 and SMTP mail server for the windows platform. It is free and contains some nice features like spam filtering, SMTP authentication, highly customized relaying options, and a built in list server.
• Microsoft Exchange Server - Microsoft messaging and collaboration server, is software that runs on servers that enables you to send and receive electronic mails.
• IMail Server
• Merak Windows Mail Server