What is the difference between Docker Mailserver and Fastmail?

Docker Mailserver: A single container mail server with SMTP, IMAP, anti-spam, antivirus and LDAP support, configured by files and environment variables. Fastmail: Paid, ad-free email hosting with calendars, contacts, custom domains and masked email addresses, built on open standards (IMAP, JMAP, CalDAV).

When should I choose Docker Mailserver?

You want a simple self-hosted mail server without a web admin panel.

When should I choose Fastmail?

An individual, family or small business wants fast, private email on its own domain without Google or Microsoft.

Docker Mailserver vs Fastmail

Docker Mailserver and Fastmail are both email server software. Docker Mailserver is open source under MIT, with 20k GitHub stars. Fastmail is a commercial product from Fastmail Pty Ltd.

Which to pick

Pick Docker Mailserver when: You want a simple self-hosted mail server without a web admin panel.
Pick Fastmail when: An individual, family or small business wants fast, private email on its own domain without Google or Microsoft.

Side by side

Docker Mailserver Fastmail

What it does

A single container mail server with SMTP, IMAP, anti-spam, antivirus and LDAP support, configured by files and environment variables.

Paid, ad-free email hosting with calendars, contacts, custom domains and masked email addresses, built on open standards (IMAP, JMAP, CalDAV).

Watch out

No GUI or webmail, and self-hosted mail brings deliverability and security work.

No office suite or file storage included, and data is held in Australia and the US.

Ready for

Production-ready (both)

Runs as

Self-hosted server

Cloud service and mobile app

Built with

Docker, Postfix, Dovecot and Rspamd

Not published

Source code

Open source, MIT (permissive)

Closed source, sold by Fastmail Pty Ltd

What the license allows

You can build it into a product you sell, as long as you keep its copyright notice.

Closed source: you use it under the maker's terms and cannot change or resell the code.

How widely known

20k GitHub stars

586 Wikipedia readers a month on phones

How established

Established: started 11 years ago, latest release v16.0.1.

Not known

Other comparisons

Fastmail vs Gmail (Google Workspace)Docker Mailserver vs Gmail (Google Workspace)Fastmail vs Proton Mail Docker Mailserver vs Proton Mail Fastmail vs Mailcow-dockerized Fastmail vs Roundcubemail Docker Mailserver vs Mailcow-dockerized Docker Mailserver vs Roundcubemail

More email servers and webmail

Every email server product and project, ranked

Both sides were judged on 2026-11-03 from makers' descriptions, Wikipedia, READMEs and GitHub data. License, age and popularity lines are worked out directly.