Other invitation emails are sent out to every family member (e.g. Adrestia, Himeros), other divine (Eris - he knows better than to not invite her, sorry, but rules of hospitality will be enforced) or friend-of-the-divines he knows. Basically, if he can get a message to you about it, he will. This includes the ones he hasn't heard from in a while. The more the merrier!