Do anyone have thoughts/feedback on Haraka - a mail server used by craigslist http://haraka.github.io/ ( Runs with Node.js + Javascript based plugin system )?
I've used Haraka standalone for a couple of custom-jobs, but I've never used it at any significant volume. That said qpsmtpd was a pleasure to use, deploy, and develop against, so I'd expect to have a similar feeling with it.
On a serious note - you'll find the Haraka developers more friendly and active than any other MTA out there. Just join the #haraka IRC channel on freenode and we're happy to help anyone.