Postal: 📨 A fully featured open source mail delivery platform for incoming & outgoing e-mail

[nebulon]

Postal is a complete and fully featured mail server for use by websites & web servers. Think Sendgrid, Mailgun or Postmark but open source and ready for you to run on your own servers. Postal was developed by aTech Media to serve its own mail processing requirements and we have since decided that it should be released as an open source project for the community.

https://github.com/atech/postal