Thanks for the reply. The problem may be worse than I thought. I may have compounded the problem further by moving items between folders and renaming pst files and I wonder about the integrity of the registry entries.

I tried to create a new empty profile to make a new start.

If I try to configure the new profile by adding a Google and/or BT email address, neither will work. I know both the email addresses, passwords etc appear correct. The error message suggests it cannot log into the server and the Google email address is incorrect:

>>>Log onto incoming mail server (IMAP): The connection to the server failed.
>>> Send test e-mail message: Cannot send the message. Verify the e-mail address in your account properties. The server responded: 530 5.7.0 Must issue a STARTTLS command first. x6sm879414wjf.24 - gsmtp

With the BT email address, I cannot log into the ser4ver and get this message:

>>> Send test e-mail message: Cannot send the message. Verify the e-mail address in your account properties. The server responded: 530 authentication required - Your email could not be sent. To fix this you must make a simple change to your email client (known as SMTP authentication)

I am now going to try and see what happens using the old Outlook profile where I have been finding similar problems.