Mail, chat, and team. Self-hosted at sessiznet.com, with no third parties between you and the people you talk to.
Postfix, Dovecot, Rspamd, and SOGo webmail. Full SMTP, IMAP, calendar, contacts.
Matrix Synapse with Element web. End-to-end encryption, persistent rooms, federation when you want it.
Mattermost for project channels, threads, and integrations. The same workflows you know, without the surveillance.