This is a list of mail server software: mail transfer agents, mail delivery agents, and other computer software which provide e-mail.

Product statistics

All such figures are necessarily estimates because data about mail server share is difficult to obtain; there are few reliable primary sources—and no agreed methodologies for its collection.

Surveys probing Internet-exposed systems typically attempt to identify systems via their banner, or other identifying features. As of December 2023[update], Postfix and exim appeared to be the overwhelming leaders in mail server types, with greater than 92% share between them, having come to prominence before 2010 in each case. While such methods are effective at identifying mail server share for receiving systems, most large-scale sending environments are not listening for traffic on the public internet and will not be counted using such methodologies.

SMTP

POP / IMAP

JMAP

Mail filtering

Mail server packages

  • docker-mailserver
  • iRedmail
  • Maddy Mail Server
  • Mail-in-a-Box
  • Mailcow
  • Mailu
  • Modoboa
  • Mox
  • Postal
  • Poste.io
  • Stalwart Mail Server

Tools

  • Swaks (Swiss Army Knife for SMTP)

See also

Notes