What are you taking on by hosting your own mail?

mailcow supplies the software for mailboxes and webmail, and your team runs the server. Someone must watch delivery failures, apply updates and recover service if the machine or a disk fails.

What should you verify with the server host first?

Check for a supported system, Docker, enough memory and storage, and support for mail traffic. Confirm the host lets you set reverse DNS, a record that maps the server’s address back to its name. The default configuration lists at least 6 GiB of RAM plus 1 GiB of swap.

Plan a separate test system before moving real mail. Keep automated app mail as its own delivery decision.

Does open-source mail hosting mean there is no bill?

The mailcow-dockerized project is GPL-3.0 licensed. Budget for the server, backup storage and the people who keep the system running.

What needs to survive a server replacement?

The backup tool can cover mail data and supporting components, including the database and mail encryption keys. Keep the configuration separately. The documented restore target is an empty, running mailcow installation.

Before starting the test copy, verify that no real receiving route points to it and that outgoing mail is blocked or goes only to an isolated test inbox. If you cannot verify both, keep the recovery walkthrough on paper.

A backup that opens in mailcow is different from a mailbox migration to another provider. Check the formats the destination accepts.

Can you explain how your team would recover mail?

Draw a fictional shop’s mail server and one mailbox. Use no server, domain changes or traffic.

Separate the machine from the mail
Write where the messages, account records, configuration and keys would live.
Choose what recovery must prove
Mark an old folder and attachment that should open in a recovered test copy.
Give recovery an owner
Name who would verify the backup and handle mail routing if the original host stopped working.