As the "someone" in question, I should clarify that the core screw-up was that the invoice emails were going to the account's "master" mailbox, which was unmoni

As the "someone" in question, I should clarify that the core screw-up was that the invoice emails were going to the account's "master" mailbox, which was unmonitored because the domain it was managing was being forwarded (IIRC I couldn't figure out how to forward the master mailbox or something). This was a while ago, so my memory may be failing me, but I'm fairly certain we had an alternate "recovery" address set up - just no one thought to send an invoice there, or call the phone number on file, or whatever... it was a "hey, you show no signs of having received the invoice, so we assume you're a PITA deadbeat and we're going to perma-delete the account for you!" Moral of the story (from my perspective) - if a customer isn't responding to your invoice, it might just be that they don't have it... try to reach on them a side channel before cutting off service!