Fran -
It's a security check. If an account fails to sign in successfully with 5 tries, then the MethodAPI (which the Outlook add-in uses) holds the account until it can be reset by us.
The regular Method sign-in now has it so that after 5 failed attempts it makes you wait 10 minutes until you can try again, and this will likely be extended to the MethodAPI in the future.
You account should be good to go now. Can you verify?
Paul