See my <a href=”http://itknowledgeexchange.techtarget.com/it-trenches/certificates-who-do-you-trust/”>blog article on Exchange certificates</a>. There is a link there to a Microsoft Exchange resource website. It may help you with this issue.
Here is another Exchange blog posting with links to Exchange resources:<a href=”http://itknowledgeexchange.techtarget.com/it-trenches/did-you-see-this-need-some-exchange-advicesupport/”>Did you see this? – Need some Exchange advice/support</a>