Outlook Continuously Asks for User Name and Password in Exchange Environment

Hello Everybody,

I have got through a problem where MS Outlook continuously asks for user name and password to authenticate the user for exchange…

This could be annoying for users and frustrating for the guys who are troubleshooting that, today I made some researches about problem and I got some solutions for it, but all are on the client side, so imagine if you have about 100 clients, you need to go to all of them and apply the fix (if it was the right solution), of course this is not acceptable at all, so I made some more searches about it into the server and I got to the bottom of it…

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Before I put my solution, I would like to clear something, which is this solution has came from experiencing the problem with my configuration, so most likely your configuration will be different from mine (maybe you will have the same configuration anyway), so just keep this in mind that there are some things different for sure…

So, now to the solution

First I had to check my installed certificate, I found 1 error in one of the SANs, so I fixed that then reapplied the certificate on the server

But still that did not solve the problem…

I noticed that the problem mostly coming on the new installed computers, so I checked all the settings on these computers, and compared them with the old computers… what I found was that the new computers have the option to use the Outlook Anywhere enabled, but the old computers don’t

I went then to check the rules and the settings related to Outlook Anywhere, and I found the following:

  • The authentication type in EMC was set to: NLTM
  • I changed it to be Basic, then checked the problem again, and it was still not solved
  • So, I checked the virtual folders on IIS for each: EWS, RPC, and OAB
  • What I found was that RPC folder was having the integrated authentication enabled on it and the basic authentication was disabled

I enabled the basic authentication on RPC virtual folder in IIS, and went back to a PC with the problem and I checked it again, and the problem has been resolved!

So, as a summary for what happened:

  • There was a problem with my certificate
  • There was a conflicting permissions on the IIS virtual folders
  • I used the Basic Authentication instead of NTLM
  • I made sure that all the folders related to outlook anywhere on IIS are using Basic Authentication

I hope that was helpful and please leave any question or comment you have…

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