I have a few email accounts set up in Outlook and, up until a few months ago when wanting to send an email, I could choose which one to send from e.g mine or my wife's.

Now when I choose my wife's email address,the email will not send. Does not seem to be any issue receiving emails to her email address, but she cannot send replies.

I note my email is set as he Default for sending, but even if I change that default to my wife's email, she still cannot send emails out.

Appreciate any clues.