Since last Thursday I have been unable to access emails on iPhone. Have tried to delete account and when I try and set it up again I get a message saying that the mail.btinternet.com is not responding. I can access emails through website. Have phoned by but they can’t help . The bt app won’t work as it says I have basic emails only which is not the case and bt couldn’t explain this one either.
if you go to MYBT does the email show as basic? are you still a BT broadband customer?
Are you presently a BT Broadband customer or are you paying for your email through a BT Premium email account?
If neither of the above your email account may have been downgraded to a BTMail Basic account which can not be used with an email client
See link
https://www.bt.com/help/email/bt-email-products