I try not to wade into discourse, but I feel like every time I see potentially urgent need for people to migrate instances on short notice, I wish Mastodon had true account portability with post migration. I think it’s beyond time to get it done.

@misty There are 2 issues. The people you follow. This is easier to migrate as you can export list from old server and upload it to new one. New one then makes all the requests to remote servers to send such and such's traffic to your instance. (Old server technically still gets those messages too).

The second partis harder. The old server needs to send authenticated "forwarding" request to everyone that follows you so they now follow you on new server.

(cont)

@misty (cont). Telling all the people who follow you to update their profile to point to your new location has security implications.

If any server were able to issue such requests, you could easily "steal" an account's followers to be moved to a fake account and that fake account would then get the DMs etc that the sender thinks will reach you but reaches the thief instead.

By requiring access to old server means you authorized the forwarding. (and your new account has been linked to old