If your email account can receive emails and you can send and receive using webmail there is obviously nothing wrong with your email password.
Having said that it may be worth changing your password to see if that "kicks" things back into life.
You should stop any other devices from checking for email. The easiest way of doing that is to turn them off or add a couple of characters to the email address so that it is not checking your account. If you have deleted the account and it is no longer on your device do not try and add it at this time.
Once you have done that, change your email password and check that you can access your email via webmail (on a browser).
If that works you should wait at least an hour to allow the servers to sync and then add the new password to Outlook remembering to remove any characters you may have added and again check it works. If it does then move onto the next device if you have one.
When entering the settings, make sure that in the Outgoing server you do not use the "use same as incoming" for the email address and password. Enter them manually.
When setting up the email account in Outlook you are best to set it up manually, using "other" and ensure that you are using the correct settings as per this link.
https://www.bt.com/help/email/manage-email-account/manual-settings/what-are-the-settings-for-outgoin...
