Mastodawn

If you want to self host email server, you can keep eye on these two projects:

1. Mox (written in Go): https://github.com/mjl-/mox
2. Stalwart (written in Rust): https://stalw.art

modern full-featured open source secure mail server for low-maintenance self-hosted email - mjl-/mox

GitHub

@ml @doncow I've been running #mailcow for a few years and very happy with it.
https://mailcow.email/

The mailserver suite with the 'moo' – 🐮 + 🐋 = 💕 | Official Blog Page

mailcow: dockerized - Blog

@jd Heard good things about it. Though I haven't tried it personally.