BTInternet mail being rejected by Google
This page describes a problem that I was seeing with some BTInternet mail addresses. For some reason email to certain BTInternet addresses were not being delivered and rejected by BT's spam filter. The anoying thing was that there were no indications of why this was the case.
In normal circumstances where you have typed in an incorrect email address you get a "bounce-back" from the email server, in this case BTInternet. No such bounces were being recieved.
To expand this further the problem was not on the Gmail side but on the BTInternet side as their mail was not being authenticated in the same way as Gmail. The BTInternet mail was not using DMARC.
I have a feeling that this situation still exists in April 2025 as I see hits on this page. If you are experiencing this problem I suggest that you contact BT and point out that they are possibly not authenicating their email correctly.
What I was seeing previously and the header of the email as recieved by my Gmail.
April 2022 - occasionally mail from a BT address was not being received on one of the GMail accounts that I administer. I previously documented a situation where mail was being intercepted as spam and Google "saved the day" by its use of ARC - Authenticated Received Chain. I have a description of ARC below.
The advice contained in the returned email message is to contact the administrator of BTInternet.com. Good luck with that one!
In my case the email in question was a Canadian address. This address was re-directed to a Gmail account where the user was in the UK. I would guess that BT would not be reponsive to a request to add the .ca domain to their list of "approved/legitimate" mail address.
In addition, the DMARC initiative is likely to be beyond the realm of BT who will possibly see this as a reason for everyone in the UK to use BTInternet.
ARC - Authenticated Received Chain
The wikipedia page for ARC: