SBS 2008 and RU3 and Outlook Repeat Login Prompt

UPDATE Exchange RU9 is supposed to fix this

On Small Business Server 2008 we have see that if you install RU3 you may start getting repeatedly prompted for log in credentials when opening outlook.

I believe that is because of some additional NTLM security that is put in place which I believe is included with RU3 based on this blurb in the update documentation

“After you install this update, the authentication mode that is set for the Web site at http://companyweb changes from the NTLM authentication to the Kerberos authentication. The reason this change occurs is because we recommend that you use the Kerberos authentication instead of the NTLM authentication.”

The solution I found so far was

  1. Remove RU3 for now.
  2. re-apply the Windows Authentication on the EWS, OAB, and Autodiscover virtual directories
    1. Open Internet information Services (IIS) Manager
    2. Expand the Server -> Sites -> SBS Web Applications
    3. Click on autodiscover -> authentication ->
    4. windows Authentication -> Disable -> enable
    5. Repeat for OAB and EWS virtual directories
  3. restart the server

Note: It may be necessary to add the root exchange URL to the “intranet sites” for on the clients

Tools -> Internet options -> security tab -> Local Intranet -> Sites -> advanced -> add ->



3 thoughts on “SBS 2008 and RU3 and Outlook Repeat Login Prompt

  1. 03/16/2011:
    I just found this article and wanted to keep it updated.

    I just installed SBS 2008 Premium R2 64-bit. It was indeed a migration from SBS 2003. I went through the BPA for SBS 2003 Migration to SBS 2008 until it was 100% error free. The migration went 100% flawlessly (1st time of 4 on this same migration type). wait…

    I go to open Outlook 2007 and I was prompted for logon information. I entered it over & over in many fashions but it wouldn’t take the logon info. I clicked Cancel 3 times and email rolled in. The logon screen repeats appearing in a few minutes. I just click Cancel 3 times & all is well. I checked 2 other users’ Outlook 2007 and it was the same. ALL 3 clients were running XP Pro & Outlook 2007 with all the latest updates.

    What, oddly, fixed it for me was THIS article! **when the article shows (in Step 4) “windows Authentication > Disable -> enable,” they actually mean just toggle it. I didn’t Disable, Apply, Enable, Apply, Restart. I simply Disabled, Enabled, OK on all 3 items the article talks about, and then Restarted.**

    I tested 2 of my original 3 test clients and they were NEVER prompted for logon info. Not when I opened Outlook. Not after 20 minutes. The weird logon prompt was gone!

    Since I want to be current with SPs from the get-go, I just installed of SP3 for Exchange 2007 on SBS 2008 Premium R2 64-bit. I followed the advice to run from an elevated command prompt, which I found in article saying this was the only way to get Rollup 9 (a just-previous-to-SP2/post-SP1 patch) to install correctly. I followed article and downloaded SP3 for Exchange 2007 (most current at the time of this post), then ran it from an elevated command prompt. I did NOT install Forefront Security (we use Trend Micro’s WFBS online scanning combined with their network-managed piece(s) and a brand new SonicWall TZ210 w/CGS).

    The clients continued to work after installation of SP3.

    • The reason is that the update changes the way IIS handles the authentication, and by toggling it you reset to the correct method.

      Great to hear that fixed it, for you and thanks for the additional info!

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