Obviously dozens of issues on this topic without a single satisfactory solution. I also raised tickets as this is a business-critical problem, but no response. It appears I've been without inbound email for the last 2 days.

Problem began with moving nameserver and webhost a couple of days ago. MX records correct and verified. But all email is bouncing with this error. Originally I thought it was just gmail, but now the problem is with all mail senders.

Hardly a recommendation for your service when this problem occurs time and again with no resolution or support.