When I joined Mastodon I was @jefftk@schelling.pt. A few days ago that server had an incident and I moved to mastodon.mit.edu, becoming @jefftk@mastodon.mit.edu. This got me thinking about a wart in the current Mastodon design: while you can normally move followers with you if you switch instances, this requires the cooperation of the instance you're leaving. In this case that instance couldn't cooperate because its domain name had expired, but I could also imagine someone having a falling out with their local admins and getting kicked off in a way that precluded transfer.

Ideally this would be like email: I send and receive email as jeff@jefftk.com. The actual server I use is gmail.com, but the people I interact with don't need to know that. If I ever want to move to a different email server I don't need Gmail's permission and I don't need to tell my contacts; I can do it entirely on my end. Similarly jefftk.com currently points to a Contabo VPS, but if I had an issue with them I could move anywhere just by adjusting my domain settings.

Current Mastodon is partway there: I can give out @jeff@jefftk.com, which uses a webfinger file (thanks, Chris) to redirect @[anything]@jefftk.com to @jefftk@mastodon.mit.edu. But then the original address is forgotten, and it only records that they're following my mastodon.mit.edu account.

One way for this to work would be that when following someone you store both their current account name and a canonical account name. Almost everything would use the former, but once a day in your instance would check whether the canonical account still pointed to the same place and adjust if necessary.

(For more discussion along these lines see Issue 3796.)