Update README.md

README.md

@@ -383,6 +383,7 @@ Simple deployment of [E-mail](https://en.wikipedia.org/wiki/Email) servers, e.g.
 - [Mailcow](https://mailcow.email/) - Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration. ([Source Code](https://github.com/mailcow/mailcow-dockerized)) `GPL-2.0` `Docker/PHP`
 - [Mailu](https://mailu.io/) - Mailu is a simple yet full-featured mail server as a set of Docker images. ([Source Code](https://github.com/Mailu/Mailu)) `MIT` `Docker/Python`
 - [Modoboa](https://modoboa.org/en/) - Modoboa is a mail hosting and management platform including a modern and simplified Web User Interface. ([Source Code](https://github.com/modoboa/modoboa)) `ISC` `Python`
+- [Postal](https://github.com/postalserver/postal) - complete and fully featured mail server for use by websites & web servers. `MIT` `Ruby`
 - [Simple NixOS Mailserver](https://gitlab.com/simple-nixos-mailserver/nixos-mailserver) - Complete mailserver solution leveraging the Nix Ecosystem. `GPL-3.0` `Nix`
 - [SimpleLogin](https://simplelogin.io) - Open source email alias solution to protect your email address. Comes with browser extensions and mobile apps. ([Source Code](https://github.com/simple-login/app)) `MIT` `Docker/Python`
 - [wildduck](https://wildduck.email/) - Scalable no-SPOF IMAP/POP3 mail server. ([Source Code](https://github.com/nodemailer/wildduck)) `EUPL-1.2` `Nodejs`