A lightweight mail server with SMTP and POP3 support. It mainly used as store-and-forward mail server with POP access to spooled messages or it can be used as a personal internet mail server.
Microsoft SMTP Server Alternatives
Microsoft SMTP Server is described as 'Configure SMTP e-mail in IIS when you want to deliver e-mail messages from your site. Mail can be delivered immediately or it can be delivered to a file location on disk where it can be retrieved for delivery later' and is an app in the office & productivity category. There are more than 10 alternatives to Microsoft SMTP Server for a variety of platforms, including Linux, Mac, Windows, BSD and Self-Hosted apps. The best Microsoft SMTP Server alternative is Postfix, which is both free and Open Source. Other great apps like Microsoft SMTP Server are Exim, OpenSMTPD, Sendmail and Courier-MTA.