on Samsung phone Keep getting msg 'couldnt verify account' even though we have used correct email and password and IMAP settings appear correct. Serious issue here, how do we sort it please?
Are you a BT Broadband customer or paying for your email through a BT Premium email account?
Log onto your MyBT and go to "Your Products" then "Email, Manage" and check what type of account you have. It should be showing as "Standard".
Does this happen when you are using your mobile devices on 4g rather than wifi while at home?
Are your mobile devices able to use other apps while connected to your home wifi network?
Have you tried turning your BT Hub off for about 30 minutes, which should force your devices to reconnect a different email server when you re-start the hub.
If they were working it is unlikely that the settings on your devices have changed but it is worth a check. The correct settings are as per the following link.