Alias Emails and Replies Not Working

Is anyone else having issues with the alias email addresses that Booking provides? We send our guests access instructions via the routing email they provide and the message text always showed up in the reservation as well. Suddenly 2 days ago, our emails are not going through, and the guests are not receiving them. They are not getting bounced back, they are just not being processed. I think it must be a technical error on Booking's side but of course when you call in, the outsourced tech support is stunned because that is not on any of their scripts. Thank you!