Tim_G,
Hope you get it sorted. I have not heard from BT. I need to contact them in order to resolve the issue. I am using my Gmail account as a work around. No problems with Gmail. It's so frustrating that BT just won't deal with the issue as they are clearly aware it's a general problem.
Do you have a "signature" in your emails. If so try removing it to see if that is the cause.
I have rung BT and reported the issue. It's now logged. Just awaiting a call back.
No response from BT despite raising a complaint. I have chased them twice now.
This is so frustrating
No signature.
Only seems to apply when sending mails TO very specific addresses.
Are they on your blocked list, or are they to the same type if email e.g gmail and have you blocked that?
If you go to settings and click blocked then you'll see the addresses of ones you've marked as spam. Look down the list and hopefully you'll see the one you're having trouble with, and delete it.