courier |
An MTA designed specifically for maildirs |
esmtp |
User configurable relay-only Mail Transfer Agent with a sendmail-like syntax |
exim |
A highly configurable, drop-in replacement for sendmail |
msmtp |
An SMTP client and SMTP plugin for mail user agents such as Mutt |
netqmail |
qmail -- a secure, reliable, efficient, simple message transfer agent |
notqmail |
Collaborative open-source successor to qmail |
nullmailer |
Simple relay-only local mail transport agent |
opensmtpd |
Lightweight but featured SMTP daemon from OpenBSD |
postfix |
A fast and secure drop-in replacement for sendmail |
protonmail-bridge |
Serves ProtonMail to IMAP/SMTP clients |
qpsmtpd |
qpsmtpd is a flexible smtpd daemon written in Perl |
sendmail |
Widely-used Mail Transport Agent (MTA) |
ssmtp |
Extremely simple MTA to get mail off the system to a Mailhub |