EnterraHost
Amazon WorkMail copies over IMAP like most providers, so the mechanics are familiar. Two things make it worth planning rather than improvising, and only one of them is technical.
AWS is retiring WorkMail
AWS stopped accepting new WorkMail customers in April 2026, and support ends entirely on 31 March 2027. After that date the console, the web app and every mailbox in it stop being reachable.
That is a fixed date rather than a warning, and it is the reason to start early rather than at the point it feels urgent. A pilot on one mailbox, a staged move in batches, and time to check nothing was missed all have to fit before the deadline, not after it.
The technical catch, if you use single sign-on
WorkMail normally supports IMAP with the account's own password and no extra setup. The exception is an organization using single sign-on through AWS Identity Center. Turning that on replaces the ordinary WorkMail credentials with personal access tokens, and from that point only a token works for mail client access, IMAP included.
If that is your setup, each person generates a personal access token from the WorkMail web app and uses it in place of a password. Test it on one mailbox before arranging the rest, because a token that does not work fails in exactly the same way as a wrong password and looks like nothing is wrong with the plan.
You will also need the IMAP server for the mailbox's AWS region, and there is a different one per region. If you do not know which region an organization sits in, the region selector in the WorkMail console says.
Getting the mail across
Once each mailbox has working credentials, whether a password or a token, the copy is the standard job. Moving your existing mail across covers the sequence, including why the DNS change belongs at the end rather than the beginning.
We can run the copy for you if you would prefer, and with a deadline this firm that is a reasonable thing to ask for. Doing it yourself is also entirely practical, and the only step with a real edge to it is the DNS switch.
A note on mailbox size
WorkMail caps every mailbox at 50 GB and will not raise it. Mailboxes here go to 200 GB with storage added in blocks, so anyone who has been pruning to stay under the old ceiling stops needing to. Adding storage to a mailbox covers how the extra room is bought.