Every time I log in and then every so often afterwards I get the pop up - you are about to override how Thunderbird identifies this site- for a now deleted mail.co.uk account. I have tried all the fixes suggested by Google but it still keeps happening and is driving me mad. It tells me the certificate is outdated or invalid and asks to confirm to permanently store the exception but just keeps coming back every time I click on confirm, it only goes away if I click cancel but then keeps coming abck.