Outlook Invalid Certificate

[Karla]

I have been using my Outlook just fine. Recieve/send message just fine.
Suddenly yesterday afternoon upon trying to send message I recieve the
following "Invalid Certificate" Microsoft Outlook could not sign or encrypt
this message becasue you have no certificate which can be used to send from
the e-mail address (then it list my e-mail address).
I went to AT&T to ensure all was fine
I have updated everything with Microsoft
I am able to receive email just cannot send.

Appreciate suggestions

 

[Milly Staples [MVP - Outlook]]

Under Tools->Options->Security, do you have the box checked to use a digital
certificate? Unless you have a current one, uncheck that box. Or update
your cert.