Merge pull request #962 from yannforget/master

Add Schleuder mailing list manager

README.md

@@ -291,6 +291,7 @@ _Mailing lists servers and mass mailing software - one message to many recipient
   * [MailyHerald](http://mailyherald.org/) - Self-hosted Mailchimp alternative that you can easily integrate with your site. Helps you send and manage your application mailings. It support email marketing and conducting the daily stream of notifications you send to your users. ([Source Code](https://github.com/Sology/maily_herald)) `LGPLv3` `Ruby`
   * [Mautic](https://www.mautic.org/) - Mautic is marketing automation software (email, social & more). ([Source Code](https://github.com/mautic/mautic)) `GPLv3` `PHP`
   * [phpList](https://phplist.org) - Newsletter and email marketing with advanced management of subscribers, bounces, and plugins. ([Source Code](https://github.com/phpList/)) `AGPLv3` `PHP`
+  * [Schleuder](https://schleuder.nadir.org/) - A GPG-enabled mailing list manager with resending-capabilities. ([Source Code](https://0xacab.org/schleuder/schleuder/tree/master)) `GPLv3` `Ruby`
   * [Sympa](https://www.sympa.org/) - A mailing list manager. `GPLv2` `Perl`
 
 #### Webmail clients