I've got a strange problem with an Exchange 2007 server running on SBS 2008. It's been working fine for users for the last 5 months, then 5 days ago they started getting a problem where Outlook would popup a window asking for credentials. If the user enters there credentials it pops up again and again, however if the user cancels the box it goes away and outlook continues to work fine. These clients all connect using Outlook Anywhere, and OWA access is also working fine.

I had thought this message box may have been to do with other POP or IMAP accounts being configured in Outlook, but it's not the case. I have re-configured Outlook Anywhere on the server but to no avail. Using the RPC diagnostic tool in Outlook shows no problems.

There are no errors showing in the event log. The server seems to be running fine, so to me this seems like either a client, or an RPC over HTTP issue, but I'm not getting anywhere finding the cause, any help is appreciated!

  • I had a similar problem to this (mine was OWA specific, but otherwise the same). I'll be interested so see if you get any good responses. – Satanicpuppy Mar 26 '10 at 15:03

This is a documented "caveat". Apply Update Rollup 9 for Exchange Server 2007 Service Pack 1 and this will go away.

See the Official SBS team's blog here:



  • Thanks very much, that solved it. Hopefully this question might make that article easier to find for others in the future. – Sam Cogan Mar 29 '10 at 12:35

This is most likely related to IIS. I would look at the IIS logs to see which URLs are being requested when you see this authentication issue and then verify that the access is set correctly on those directories in IIS. If you can find another OWA install that is working, it may be worth while to run a diff program to compare your two metabase.xml files.

Remember, that Exchange 2007 will use IIS for several things including autodiscover, offline address books and Exchange Web Services (free/busy, etc). So even though you have a MAPI connection for the mailbox, IIS is still being utilized by Outlook.


I'm sure this could be any number of things but one thing I know can cause this is if your autodiscover..com CNAME was suddenly deleted. Make sure the affected PCs can still reach that record.

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