This issue is new to our client that is running Outlook 2010 (on a Win 7 machine) and connecting to an Exchange 2007 box. There is only one Exchange box. I have tried the suggestions with assigning the certificate to the “Trusted Root Certification Authorities” area. I have launched the “certmgr.msc” and see the “mail.domain.com” certificate listed. I deleted and readded it as well. We have a signed 3<sup>rd</sup> party certificate that does not expire until 2016. I have uninstalled and reinstalled Outlook 2010 on the machine. I have also unchecked the “use Cached Exchange Mode” in the “Change Account Settings” area. I have been searching for a solution for this for two weeks now. Everything I have read has to do with Exchange 2010 and Outlook 2010 working together. I have attached the error, I’m sure most that are reading this have seen it. I’m not sure if there is a setting I’m missing on the machine, or what is going on. Thank you to all that have read this. I look forward to additional advice for a solution.
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