Apprise allows you to send a notification to almost all of the most popular notification services available to us today such as: Telegram, Discord, Slack, Amazon SNS, Gotify, etc.

MIT

Python

Asterisk

Easy to use but advanced IP PBX system, VoIP gateway and conference server.

GPL-2.0

Courier MTA

Fast, scalable, enterprise mail/groupware server providing ESMTP, IMAP, POP3, webmail, mailing list, basic web-based calendaring and scheduling services.

GPL-3.0

Exim

Message transfer agent (MTA) developed at the University of Cambridge.

GPL-3.0

Kamailio

Modular SIP server (registrar/proxy/router/etc).

GPL-2.0

OpenSMTPD

Secure SMTP server implementation from the OpenBSD project.

ISC