Outlook Continually Prompts for Credentials
Microsoft Outlook users with Exchange mailboxes in a Small Business Server 2008 network will be continually prompted for login credentials when they are disconnected from the Small Business Server network, but where Windows detects some other network connection (for example, when using a home broadband router, or a wireless broadband adaptor).
This occurs because SBS 2008 configures Outlook to use RPC over HTTP (“Outlook Anywhere”), but the server is not configured to allow it.
- In Outlook, go to the Tools menu, and choose Account Settings.
- Click on the connectoid with type Exchange and click Change.
- Click More Settings.
- Click the Connection tab.
- Untick Connect to Microsoft Exchange using HTTP.
- Click OK.
- Click Next.
- Click Finish.
- Close and re-open Outlook.
This issue may also occur with Exchange 2007 Service Pack 1. Install the latest service pack, or Rollup Patch 9.