Logging into the account was just a test.
You are removing the account from the phone, then adding it back using the values I gave, I have repeated these below.
use these settings when adding it please
Put the name you want people to see when they get mail from you in the Name field.
Enter your BT Business username in the Address field. For example,[email protected]
or, where you have registered a custom domain,[email protected]
Enter your BT Business password XXXXX the Password XXXXX
In the Description field enter the name you want to use to identify the account.
Tap Next. If you get an error message at this point, tap OK.
Make sure that POP is selected at the top of the screen.
In the Incoming Mail Server section, change the Host Name to
Now enter 995 in the Server port and set SSL to on.
Then scroll down to the Outgoing Mail Server section and change the
Host Name to smtp.office365.com.
Now enter 587 in the Server port and set SSL to on.
Your settings will now be verified and you'll then see your Account screen. This may not happen automatically, so simply tap btconnect account to access your email.
Let me know the results please