Oct 13 2019
Our SSL certificate is expired today, but we renewed it two days ago.
Today, Outlook pops up a security warning for all user saying "The security certificate has expired or is not yet valid." I clicked the "View Certificate" button, it shows the old certificate.
I checked the local computer certificate store and found the old certificate is in the trusted store, I removed it, but it didn't help. Outlook still remembered the old certificate.
OWA is fine and the certificate is updated.
Thanks in advance!
Oct 14 2019
What was that certificate used for? Exchange? AD FS? Have you made sure to update it on all relevant endpoints? Removing it from the local store doesn't make a difference if Outlook is hitting a server with said certificate still installed.