Move Mail to New Mac

Having recently purchased a new Mac, I decided to start with as much of a “clean slate” as possible and avoid using Migration Assistant to copy hundreds of gigabytes of data I don’t need.

But I did need my email, all of it. And the old way of copying the ~/Library/Mail folder and .plist isn't sufficient under macOS Sequoia any more.

So, if it helps anyone else, this is what you need to copy from your old to your new mac (I did it with simple scp commands, but there's many ways to achieve the same!)

~/Library/Mail
~/Library/Preferences/group.com.apple.mail.plist
~/Library/Accounts (this is the new one)

Copy all of these across (and make sure you chown -R <username>:staff ~/Library/Accounts ~/Library/Mail ~/Library/Preferences/group.com.apple.mail.plist afterwards then reboot or log out and in again before opening Mail.

The key change seems to be that accounts are now stored separately, so if you only copy the Mail folder (even with the plist), Mail doesn’t know the accounts exist.

This worked for me, hope it helps someone else, YMMV.