GreXXL, because if I've asked a question, or expect a response to posted information, and the thread is locked before anyone has been able to respond, I shall not know that I am unable to receive a response, otherwise.
I receive all of my notifications via e-mail (albeit, some are first routed via Atom), because I utilise so many online platforms. Proactively checking notifications on all of the ⪆ 10 Flarum forums that I utilise isn't feasible.
If e-mail is expensive, an Atom feed that provides the same would be acceptable; the method by which the notifications are posted merely need to be standardised and consumable (but not WebNotification; that's too ephemeral).
