Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
Inbucket - Inbucket is an email testing application; it will accept messages for any email address and make...
Sendmail - Sendmail is a general purpose internetwork email routing facility that supports many kinds of...
Exim - Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.
MailHog - MailHog is an email testing tool inspired by MailCatcher, but easier to install.
msmtp - msmtp is an SMTP client.