First off, I originally posted this question in an Exchange forum and received a reply from the moderator that leads me to think this might be an Active Directory issue.
Second, I am not an AD administrator. When I have posed this question to our AD administator, I have gotten the brush off. I am posting this message in the hopes of receiving some objective opinions.
Finally, I am not trying to solve an existing technical issue. I am simply trying to collect more information so that I can gain a better understanding of email encryption issues.
Recently, I have seen three cases were a user was having email encryption problems, and in all three cases the issue was caused by an expired default certificate in the address book. In all three cases:
- The user had one valid certificate listed in AD.
- I opened MMC on the client machine and added the Certificates snap-in, and found only one certificate installed on the machine, and it matched the certificate listed in AD.
- I looked up the user in the address book, did a right-click > Add to Contacts > Certificates button on the ribbon, and found that the default certificate listed for the user was expired.
In one case, the default certificate listed in the address book expired in 2012. If that expired certificate is not in AD, and it's not installed on the client machine, then where is it coming from? It has to be coming from somewhere.
Is it possible that AD is holding on to old certificate information in a location that is not visible through ADUC? If so, is it possible to clear out old certificate information?
Thanks in advance for any help that you can offer!
--Tom