This is more complicated than I thought.
Firstly, I have changed nothing at all related to my email accounts, or routing, for many years, apart from resetting my talktalk email password to see if that helped (which it didn't).
However, my normal email address is actually not the gmail address, but an intermediate address belonging to a domain I registered over 15 years ago. Emails sent to that are all, without exception, sent to my gmail account. This has worked without any issues for all of that time. And still does, except....
If I send from my talktalk email account to my normal email address, it gets treated as spam when forwarded on and received by gmail. If I send directly to my gmail account instead, it is not treated as spam!
It is difficult to say exactly when this problem started, but something like a month ago. I test my talktalk account quite regularly, sending to my normal email account, and this worked until recently. So something, somewhere, has changed. I am aware that there have been some changes in the talktalk email system, so I am wondering whether that is related to this problem.
All other emails sent by all other parties to my normal email account are still processed normally, as they always have been, and forwarded on to my gmail account without any problems. So I think there must be some changed interaction between the talktalk email and the forwarding domain system that in some way removes some level of authentication that gmail expects.
Can anyone help?
