I have a custom domain email routed to a gmail address, has been working fine for 3 years and suddenly emails have been failing to arrive with the error message: Timeout while connecting/communicating to the upstream: network error: timed out.
DNS has been set up correctly and unchanged. Most emails are successfully forwarding, but some email addresses are retrying multiple times, and even a another gmail address is getting “Recipient inbox full” trying to send to my address.