Posted on Apr 21, 2014

For Outlook 2007 users; you must be running Outlook 2007 SP3 or no fix will resolve this issue. Once you have installed the necessary patches the issue should be resolved. If this does not fix the issue, please verify that the ‘Logon Network’ security is set to ‘Password Authentication (NTLM)

This setting can be found in tools>accounts>account settings>advanced settings.