My SPF: any role in whether 3rd party email gets to me?

[jingars]

BT is my ISP, and has been for some years. I have a domain registered with 123 Reg to make the family's email addresses ISP-agnostic. Email forwarding from 123 Reg to BT is in place for my self and my wife. Email forwarding is also in place to Gmail for the sprogs' email.

In the last 10 days or so, I have started receiving emails from [e-mail] with;

This is an automatically generated Delivery Status Notification.      

Reason: There was an error while attempting to deliver your message with [Subject: "The subject of each email"] to my_wife'[e-mail]. It has been in queue too long, and will not attempt delivery again.

Reporting-MTA: dns; p3plwbeout27-02.prod.phx3.secureserver.net [45.40.130.60]
Received-From-MTA: dns; mailex.mailcore.me [94.136.40.145]
Arrival-Date: Thu, 22 Apr 2021 06:12:31 -0700

Final-recipient: rfc822; my_wife'[e-mail].

On checking the BT forum I found that I was not alone, and that a number of other customers with the same email config (domain administered and email forwarded by 123 Reg to BT email inboxes) are also affected.

BT advised that they have made changes to their config. They also advised that we should update our SPF record with 123 Reg, but then refused to tell me what we should include in that record. Like most on the BT support forum thread, at that time I did not have a SPF record configured.

To my question; all of my searching has produced results which (understandably) detail the role the SPF record plays in advising the correct source of an email, and so if I were to receive errors when sending emails I can understand that the SPF record may have some bearing. However, as I am the recipient and not the originator for the emails going to error, what role (if any) does the SPF record of a recipient have in this scenario - or has BT thrown a curve ball in to the conversation as a distraction from the root cause?

I am way, way out of my depth and the BT community forum thread seems to be in a loop. Any opinions gratefully received. TIA.

[colin79666]

Yes it will have an impact if you are receiving email to a 123 reg mailbox and then forwarding it to a bt mailbox. In that scenario the email is effectively being resent.

123 reg have a support page on the subject:
https://www.123-reg.co.uk/support/domains/how-do-i...

If you are using bt to send as your custom domain you also need to add their details to the spf record, otherwise your sent email may get caught in spam filtering.

Edited by colin79666 on Tuesday 27th April 08:18

[buggalugs]

You'll be better off doing it the other way around if poss, getting the end email account to pull in the emails from 123 rather than forwarding. I know gmail can do this not sure about BT.

[jingars]

Thanks both.

As far as I am aware, emails we have been sending via BT have all made it to their destinations.

I have added a SPF record to the domain record via the 123 Reg dashboard, and have added btinternet.com as a permitted sender via the "Include" bit, but to be honest I haven't the faintest idea what I am doing.

Email hosting from 123 Reg is an extra cost option which I am reluctant to take as BT should be up to the task of correctly administering their network - it seems clear that recently they have made a change which has adversely affected the previously stable state of affairs.