My certificate was working fine to sign emails yesterday. I don't encrypt, just sign.

Now I am unable to sign.  My certificate reports as valid.  (Outlook 2013 - Windows 8.1 Enterprise)

Found a number of entries for mismatched email addresses and for encrypted emails.  None of those suggestions apply as my email address is contained within my certificate despite the statement in the error message that a certificate matching my email address could not be found. 

Full error text:

Invalid Certificate

Microsoft Outlook cannot sign or encrypt this message because there are no certificates which can be used to send from the e-mail address 'xxxxxx @ yyyyy.zzz. Either get a new digital ID to use with this account, or use the Accounts button to send the message from an account that you have certificates for.

• Edited by BRuce Young Thursday, August 27, 2015 12:48 AM