Migrate

Moving mail from any IMAP server

The fallback that always works, and the one to use when there is no connector for where you are leaving.

Read this part first

What this connector cannot do. These are the facts that decide how long your weekend is.

Without a master user you need working credentials for every mailbox. On a large domain that is the whole cost of the migration.
Server-side rules, filters and autoresponders are not visible over IMAP and are not copied. Recreate them after the move.
A source that throttles or complains can be given a per-mailbox transfer ceiling and fewer mailboxes at once.

1
Add the domain here first
Records published and verified, MX untouched.
2
Add the mailboxes
Paste the addresses — plain IMAP has no way to list a server’s users — with a password for each unless you have a master user. This is the part that scales worst, and is the reason the panel connectors exist.
3
Run the full copy
Mail, folders and flags, resumable, while the old server is still live.
4
Change the MX, then sync the delta
As with every other source.
5
Walk the checklist
Clients reconfigured, rules recreated, old server kept until you are sure.

The source hostname and port, and whether it uses TLS.
A master user (a Dovecot or Courier admin login) if the source has one; otherwise a username and password for each mailbox.
Network access from your new server to the source.