I administer three domains. I've received upwards of 15 of these attempts already. I administer three domains. Yeah, they hit my mail hub over the weekend too. Prodigy Services Corp. Hope this helps you.
Hosts vanish from the net all the time.
If yours does too, it can't be that bad. As a list manager, I'm going to drop addresses at your host just like any other address that suddenly becomes unreachable. It's a waste of your time and if it is important, they will resubscribe anyway. Yeah, they hit my mail hub over the weekend too. I sent a note to the list earlier today, but I don't know if it ever arrived.