[outages] Cox MTA's rejecting e-mails?

I've seen Cox MTA's bouncing e-mails to valid recipient addresses with SMTP 550 5.1.1, "invalid recipient." According to one of the support people I spoke to, this is a widespread problem that engineering is aware of, but it's been at least a week in some cases, and there's no ETR. Is anyone else seeing this; is anyone from Cox mail ops on this list who can confirm? Apologies if this should go to a mail ops list, but that's not my primary area of responsibility and I don't subscribe to such.