Mail-in-a-Box is a one-click mail server appliance for Ubuntu, bundling SMTP/IMAP, webmail, DNS, TLS automation, backups, and an admin control panel.
15.4k stars1.5k forksCC0-1.0last commit Actively maintained
9 self-hosted Proton Mail Professional alternatives
Hosted, privacy-focused email service for organizations that provides custom domains, admin controls, encrypted mailboxes with end-to-end and in-transit encryption, user and group management, business plans with audit/management features and secure integrations.
Alternatives to Proton Mail Professional
All-in-one open-source mail and collaboration server with SMTP, IMAP, JMAP, CalDAV, CardDAV, and WebDAV, plus integrated anti-spam and phishing protection.
14.4k stars909 forkslast commit Actively maintained
Mailcow is a dockerized mail server suite providing SMTP/IMAP, webmail, anti-spam/anti-virus, and domain/mailbox administration via a unified web UI.
13.3k stars1.8k forksGPL-3.0last commit Actively maintained
#4
Mailu is a full-featured mail server distributed as Docker images, providing SMTP/IMAP/POP3, webmail, administration UI, and built-in security and anti-spam features.
7.5k stars997 forkslast commit Actively maintained
#5
Automated open-source mail server installer bundling Postfix, Dovecot, webmail, anti-spam/antivirus and LDAP/SQL backends for mainstream Linux/BSD.
1.8k stars260 forksGPL-3.0last commit Actively maintained
Cyrus IMAP is a secure, scalable mail server providing IMAP/JMAP email plus CalDAV/CardDAV contacts and calendars, with ACLs, quotas, search, and replication.
643 stars175 forkslast commit Actively maintained
Simple NixOS Mailserver provides NixOS modules to deploy a full email server with SMTP/IMAP, spam filtering, DKIM/DMARC/SPF, and TLS automation.
Activity unknown
Self-hosted enterprise collaboration suite providing email, webmail, calendaring, contacts, and administration for organizations.
Activity unknown
#9
Open-source webmail and groupware offering email, contacts, calendar, cloud drive, tasks, notes and an admin control panel for multi-tenant email services.
Activity unknown
What replacing Proton Mail Professional actually involves
Every option on this page is open source and free to run on your own hardware, so you own the data and there is no subscription to cancel. 6 of 9 shipped a commit in the last six months. Licences in this list: CC0-1.0, GPL-3.0. In exchange you take on hosting, backups and updates yourself.
Browse everything in Email Servers (SMTP/IMAP).
