[Alupis]

The vanity domain must be registered with GoDaddy, and doesn't provide attachment screening nor email encryption.

So... It's artificially gimped for no real reason.

[extra88]

It's not supported but apparently it's possible to use a personal domain for Microsoft email without using GoDaddy as your registrar.

https://www.reddit.com/r/Office365/comments/ft15pk/use_perso...