convenient.email

Your IdP must provide a unique primary email address for each user. In some IdPs, the primary email address might not be a real email address. For example, it might be a Universal Principal Name (UPN) that only looks like an email.

Please, don't document like this.
Hypolite Petovan friendica (via ActivityPub)
Why not?
This must be an email address
Well no
But it should look like one


Maybe?
It looks like the fault of the field namer and a technical writer without enough background
Hypolite Petovan friendica (via ActivityPub)
Ah, got it.