Hey all, we're a group of email infrastructure industry veterans, and before that were contributors to PHP and MySQL, and we decided that it was time for there to be an Open-Source MTA as scalable and flexible as the commercial options, and so KumoMTA was born.

We just cut our first production release and hope you can give it a try, it's great for all forms of email sending, but excels in high-volume, multi-tenant environments.

Announcement is linked to in the post, repo is at https://kumomta.com/repo