Sometime, valid certificates issue faced by the user, so in such case, validation of valid certificates most important:
- Open Outlook –> Click Tools –> Options
- Select the Security Tab –-> Click on Settings
- Under Certificates and Algorithms –-> Click choose and select the correct certificate.
Check server certificate validation:
- Open Active Directory Users and Computers
- Under the User container –-> Select the user –-> Properties
- Select the Published Certificates Tab –-> Remove the other certificates which are not valid.