But can you host it ? (Can't find much on federation). I use fastmail and a cust...

But can you host it ? (Can't find much on federation).

I use fastmail and a custom domain for my email. If I'm unhappy with the service I can migrate or host it.

If you can't leave having your own domain is not much help.

Note: I believe webfinger are supported by Mastodon too, so not so special of a feature.