Tools

Email (IMAP/POP3), contacts and calendar server.

A modern IRC server (daemon/ircd) written in Go.

Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots.

POP/IMAP/SMTP/Caldav/Carddav/LDAP exchange gateway allowing users to use any mail/calendar client with an Exchange server, even from the internet or behind a firewall through Outlook Web Access.

An open-source platform for legally compliant email archiving.

Mobile messaging platform with a focus on performance and scalability.

Web interface for multi-platform voice switch called FreeSWITCH.

Mail-in-a-Box helps individuals take back control of their email by defining a one-click, easy-to-deploy SMTP+everything else server: a mail server in a box.

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

All-in-one mail server that implements SMTP (both MTA and MX) and IMAP. Replaces Postfix, Dovecot, OpenDKIM, OpenSPF, OpenDMARC with single daemon.