I'm doing some development which will involve reacting to emails, and I'd like to use a local IMAP mail server for this.
I currently use Devnull SMTP server for testing of sending emails, but this just logs and discards messages, it doesn't do IMAP for checking incoming emails/mailboxes.
I don't need/want a full-blown server, just something lightweight I can easily start/stop as required.
Multi-platform is preferred, but feel free to provide answer for specific platforms also.
(A POP3-based server would also be acceptable for development use, since I'll be supporting both in my code anyway.)
Take a look at hMailServer.
I consider JAMES the best mail server for development. And its portable too. Fully written in Java.
Mercury Mail Server is a full featured mail server (minus webmail), however it is very light and should meet your need: Mercury Mail Server
Edit: Forgot to mention Windows/Netware only
Check out courier for unix-based machines. I've run it for quite some time on a linux machine, and it's very nice. You can easily enable/disable the features you want, including SMTP, POP, IMAP, SMTP Auth, SSL versions of protocols, etc.
exim works nice even in windows via cygwin.
Mdaemon is an excellent windows MTA. Lots of good reasons to use it in production too. Another different option is to use Gammadyne mailer in server mode.
来源：https://stackoverflow.com/questions/770098/whats-a-good-mail-server-for-development-use