I have upgraded a client's exchange 2003 to 2010 and now outlook users receive Certificate error message every time they open Outlook 2007.
the client is not using public certificate and they are not intending to deploy one anytime soon. but there's about 1000 users who are domain joined and they have the Certification Authority certificate installed properly.
One thing I did notice which is when I create a new Outlook profile for any user, I get the Certificate warning just once and then next time it disappear.
but with the old account no matter how many times I accept the Certificate warning, if I close it and open outlook again i'll get the warning.
Is there anyway to do something to fix this without needing to manually go to those 1000 PCs and fix it?