Hi All,
I have both personal Outlook 365 subscription and Outlook 2019 from my company. I have two office 365 email accounts on different domains added to outlook. Both accounts have different signature certificates. One is signed with self signed CA certificate of my organization and one is from Global Sign.
This setup works for some time for signing/ecrypting emails but from time to time I caught following or similar errors when answered to encrypted emails:


Our internal IT-Support found that it is because outlook cannot pick proper certificate. I was suggested to set following registry flag to suppress check for certificate.
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Security]
"SupressNameChecks"=dword:00000001
But that resulted to issue that outlook uses the same certificate for both account that is not correct for the second account. Moreover Outlook does not allow to change certificate that should be used and complains that certificate cannot be found.
When I removed the flag previous behavior was not restored and Outlook continues to complaint that it cannot find certificate.
Please help me to solve this certificate issue as our IT support cannot find a solution.

