Outlook, S/MIME, IMAP and Cert Expiration

Question

How does outlook handle encrypted IMAP-Mails after the certificate/key the mail has been encrypted with expires?

To still read the e-mail, that is encrypted on the IMAP-Server, I would need the original private key for which the mail was encrypted with. But what do I do if the certificate for the key has expired? How do Outlook or other clients handle this?

Answer 1

Outlook will warn you with a visual indication that the certificate used to decrypt the message is no longer valid. In the message window, you'll see a red horizontal line right above the body of the message, and in place of the lock icon which normally appears to designate an encrypted message, you'll see a yellow warning icon.

Needless to say, in order for Outlook to decrypt the message, you'll need to have the (expired) certificate installed in your certificate store.