I have SBS 2008 SP2 running Exchange 2007. This is a new install. I have not added the SSL yet, I'm using the default SSL cert created by the system. At first everything seemed to work find. I join one system to the domain without issue. Or at least I thougth. I continued to finish setting up various componets. I was able to send and receive via Exchange / OWA without issue..so I continued to install other componets. When installing Symantec Mail Security I was told Messaging API and Collaboration Data Objects 1.2.1 componet is required. After downloading, installing and reboot of the server Outlook on the workstation keeps asking for a user name and password. At first it will connect, send and receive but a minute or so afterwards Outlook will ask for a User name and password. The workstation appears to be able to access other resources from the server without issue. This only appears to be an Outlook issue. Any suggestions?

Try to remove the workstation from the domain and rejoin as a test?

Please disable the third party software on the SBS server at first Please verify if the problematic user can access mailbox correctly via OWA Please verify that the window will prompt for credential on outlook for newly created mailbox and mail profile Please increase the diagnostic logging level on the SBS server, reproduce the issues, and then monitor the related event in the application log on the server · MSExchangeIS\9000 Private\General · MSExchangeIS\9000 Private\Logons · MSExchangeIS\9000 Private\Access Control Diagnostic Logging of Exchange Processes What’s the outlook client version? On the problematic client, please run Test E-mail AutoConfiguration on the internal outlook client, and then check the output (Reference) Please verify the configuration on the virtual directories on the server Default settings for Exchange-related virtual directories in Exchange Server 2007Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.