We have been having quite a few reports recently of users with a BT Internet domain having problems with receiving emails. BT tend to be quite aggressive when it comes to marking an email address as spam.
Unfortunately, BT's servers tell ours that they have received the email. Beyond this point, we do not have any control. BT at this point do not then forward the email to the intended recipient.
You'll need to send these customers an email outside of our software to get around this problem.
Please send us your btinternet addresses so that we can build a case to take to BT and give them a firm poke.
To give you some more detail, BT accept our emails and send us a receipt to say they have received them. At this point, our systems update to show that the email has been successfully delivered. BT should now pass these emails on to the intended recipient - but they are not doing this. This is therefore something beyond our control.
If the email was marked as "spam" in most cases, in that first step, the receipt we receive would say that the email has been marked as spam and either be categorised as a "soft-bounce" (Temporary issue - no action required) or a "hard-bounce" (Permanent issue - action is required). With these notifications, there is often something we can do or at least help with to resolve the email issues.