The settings for BT mail ARE industry standards.
@R_A_898wrote:
I believe the ultimate problem lies with BTinternet emails and how they are set up compared to industry standards.
Can you explain how if the BTMail settings for email clients/apps are not " to industry standards" can the hundreds of thousands if not millions of people including yourself when you use Thunderbird, manage without any problems.
I would suggest that the problem is with 29 year old Classic Outlook and its compatibility with Windows 11.