Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
MailHog - MailHog is an email testing tool inspired by MailCatcher, but easier to install.
OpenSMTPD - OpenSMTPD is a FREE implementation of the server-side SMTP protocol as defined by RFC 5321, with...
Mailosaur - Email Testing for QA & Development Teams.
Microsoft SMTP Server - Configure SMTP e-mail in IIS when you want to deliver e-mail messages from your site.