Migrating from another system

A new Stalwart server often replaces an existing system that already holds mail, calendars and contacts, and its users expect to find that data on the new server. Moving it is a separate task from the installation, and the right procedure depends on where the data comes from:

From a Stalwart 0.16 deployment, Upgrading from Stalwart 0.16 copies the whole deployment into a new 1.0 store while 0.16 keeps running, with a short maintenance window at the end. It needs disk space for a second copy of the data store, and the migration overview compares it with the account-by-account procedure below.
From another mail server, a hosted service, or another Stalwart server of any release, the migration section describes how accounts are moved while users keep working, using a migration proxy that routes each user to the server currently holding the account and a tool that copies mail, calendars, contacts, filters and files one account at a time. Hosted services such as Google Workspace and Microsoft 365 are covered in Migrating from hosted services.
Between storage backends of the same server, for example from RocksDB to PostgreSQL, Database migration exports the data store and imports it into the new backend.
Between 1.x releases of the same server, no migration is needed, and Upgrading describes the procedure.