Hello,

Outlook Anywhere has been working in our environment internally for a few years now, however over the past few months I have been noticing that if I close Outlook and restart it, Outlook with continually prompt for my password and not accept it.

I have found that the cause is that the Proxy authentication settings is being changed from basic (which works) to NTLM which will not work.  Changing the setting back to basic will allow the user to log in, but the setting will change back to NTLM shortly afterwards and the user will not be able to log back in if they close Outlook and restart it.

This is happening both internally and externally, but it's also happening on users' home machines that are not even domain members.  We are not using the 2010 Exchange gpo and I'm not aware of any way that settings can be changed on a client that is not even a domain member!  What could be causing this setting to change??

Thanks.

This problem is likely a misconfiguration on the autodiscover service on the server. The ClientAuthenticationMethod parameter is used by the autodiscover service to tell the client what authentication method to use. If you change the authetication method manualy, the next time the client contacts he autodiscover service it will be changed to the value set by the ClientAuthenticationMethod parameter. You need to set the ClientauthenticationMethod to NTLM.

Disabled the Outlook-Anywhere on 2 of the non-production CAS servers
Verified that the production servers are having just NTLM-Authentication on the servers

More Reference:
http://technet.microsoft.com/en-us/library/dd439374(EXCHG.80).aspx

Cheers,
Tony Chen
Forum Support
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Hi Tony,

Thanks for your reply.  I actually need to go in the other direction, and ensure that this setting is set to basic and not NTLM, however your assement of the issue looks correct to me.  I can see through the gui that this setting is correct(basic) and I have found this command in order to set this to basic in the shell:

set-OutlookAnywhere -IISAuthenticationMethods <Basic or NTLM>

However, I don't see where I can simply view the current setting from the shell.  Simply replacing set with get doesn't seem to work.  How do I view the existing setting from within the shell?

Thanks.

Hi,

I was wondering whether issue has been resolved yet. Since the issue might be caused by Exchange site, better to post your question to the forum for Exchange

http://social.technet.microsoft.com/Forums/en-US/category/exchangeserver/

The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thank you for your understanding.

Cheers,

Tony Chen

I know this is an older thread but wanted to post incase others ran across the same issue. We experienced this A LOT after moving users to EX2013 - we knew Autodiscover was configured correctly but couldn't determine why come clients kept changing back to Basic Auth. Ended up being only Outlook 2010 MSO or SP1 clients. Once we updated them to Outlook 2010 SP2 everything worked fine.