Comparison of mail servers

This is a comparison of mail servers: mail transfer agents, mail delivery agents, and other computer software that provide e-mail services.

Linux based mail servers are built using a number of components because a Linux environment is, by default, a toolbox operating system. A stock Linux server already has internal mail. To allow the server to send external emails, a Mail Transfer Agent such as Sendmail, Postfix, or Exim is required. Mail is read either through direct access (shell login) or mailbox protocols like POP and IMAP.