Outlook Anywhere proxy changed from Basic to NTLM for external users

Question

I have a Exchange 2013 environment that is also running Exchange 2010 coexistence (migrating). What is happening is autodiscover is handing out NTLM for the proxy settings and not basic. However when it is using NTLM we seem to get the password prompt over
and over. If I manually changed it to Basic then it works fine, but when autodiscover goes again it changes back to NTLM and prompts that the Administrator made a change and you need to restart Outlook.
I checked Outlook Anywhere and all my servers have Basic set for external users and NTLM set for internal.
I only have a few mailboxes on 2013 and 2010 mailboxes seem not to have a problem.
Here is an output for Outlook Anywhere on all six servers:
Identity                           : CAS01\Rpc (Default Web Site)
ExchangeVersion                    : 0.10 (14.0.100.0)
ExternalClientAuthenticationMethod : Basic
InternalClientAuthenticationMethod : Ntlm
IISAuthenticationMethods           : {Basic, Ntlm}
Identity                           : CAS02\Rpc (Default Web Site)
ExchangeVersion                    : 0.10 (14.0.100.0)
ExternalClientAuthenticationMethod : Basic
InternalClientAuthenticationMethod : Ntlm
IISAuthenticationMethods           : {Basic, Ntlm}
Identity                           : CAS03\Rpc (Default Web Site)
ExchangeVersion                    : 0.10 (14.0.100.0)
ExternalClientAuthenticationMethod : Basic
InternalClientAuthenticationMethod : Ntlm
IISAuthenticationMethods           : {Basic, Ntlm}
Identity                           : EXCH2K13-01\Rpc (Default Web Site)
ExchangeVersion                    : 0.20 (15.0.0.0)
ExternalClientAuthenticationMethod : Basic
InternalClientAuthenticationMethod : Ntlm
IISAuthenticationMethods           : {Basic, Ntlm, Negotiate}
Identity                           : EXCH2K13-02\Rpc (Default Web Site)
ExchangeVersion                    : 0.20 (15.0.0.0)
ExternalClientAuthenticationMethod : Basic
InternalClientAuthenticationMethod : Ntlm
IISAuthenticationMethods           : {Basic, Ntlm, Negotiate}
Identity                           : EXCH2K13-03\Rpc (Default Web Site)
ExchangeVersion                    : 0.20 (15.0.0.0)
ExternalClientAuthenticationMethod : Basic
InternalClientAuthenticationMethod : Ntlm
IISAuthenticationMethods           : {Basic, Ntlm, Negotiate}

Answer 1

Hi,
Please refer to the following KB to set the Outlook Anywhere settings on Exchange Server 2013 Client Access servers:
http://support.microsoft.com/en-us/kb/2834139
If it doesn’t work with the resolution above, please do the following checking in ADSI Edit:
1. In Adsiedit, expand Configuration-->CN=Services -> CN=Microsoft Exchange -> CN=domain -> CN=Administrative Groups -> CN=Exchange Administrative Group -> CN=Databases.
2. Right-click the listed database > Properties.
3. Check whether the msExchHomePublicMDB value is set to an available value. Please change the value to <not set>.
4. Click OK.
Then check whether the issue persists.
Regards,
Please remember to mark the replies as answers if they help, and unmark the answers if they provide no help. If you have feedback for TechNet Support, contact [email protected]
Winnie Liang
TechNet Community Support