In my company I recently installed a second server (Windows 2012 r2) in addition to the existing Windows SBS 2008 Server, which was also hosting the Exchange server. Then I switched to Office 365 and turned the Exchange Feature off. However, Since about two weeks, the clients are asked to install a certificate from the SBS Server (wich expired in 2013) when Outlook is started.
Is there a way to stop the certificate asking to be installed?