Emails being forwarded to BT email clients are not be forwarded to BT clients.
In one case the BT client receives the email with attachments missing.
Another BT client receives nothing, the sender receives a response for the same email - Warning: message 1kPqbE-0012RK-6A delayed 24 hours - Please add a SPF record for the domain (SPF record exists on senders domain). The email content has a few non-provocative words and a small 56lb jpg file.
Non-BT clients do not experience issues with the same email which rather implies BT is having issues with its new BT platform. I believe the issue is different if the recipient is using web or client systems.
These issues are happening randomly and re-occur from time to time
I have experienced a similar problem. Someone with an outlook.com e mail account made several attempts to send me an e mail with a link to a OneDrive document it did not arrive at two bt.com e mail addresses. When sent to a gmail account no problem.