Our active directory domain is domain.local. Users have usernames uname@domain.local. Their email addresses are however, uname@domain.com. When the user is on their computer that is connected to the domain, the outlook profile is configured automatically and they experience no problem. However, when a user tries to login from a non AD computer from outside our network, autodiscover does not work. I checked autodiscover connectivity through https://testconnectivity.microsoft.com/ and it works (provided I enter uname@domain.com but domain.local\uname as authentication). The reason is probably that autodiscover tries to use login in the form uname@domain.com which fails as the username has to be uname@dt.local

What I want is a seemless autodiscover without the need for the users to enter their credentials again (using domain.local domain) and I want to keep their internal logins in the form uname@domain.local.

How do I achieve that?

add UPN value under AD for your email domain name.

add UPN value under AD for your email domain name.

• Marked as answer by Leosenko 19 hours 3 minutes ago

Hi,

Please run the below command to check your setting:

Get-Mailbox -Identity UserName | fl *name*,*address*

As Vishwanath mentioned, we can Add a UPN Suffix to Active Directory, please take the following steps:

1.Open Active Directory Domains and Trusts.

2.In the console tree, right-click Active Directory Domains and Trusts, and then click Properties.

3.On the UPN Suffixes tab, type an alternative user principal name (UPN) suffix for the forest, and then click Add.

4.Repeat step 3 to add additional alternative UPN suffixes.

After finishing the actions, you should see the new UPN suffix available in the list when setting the username.

For more detailed information, please refer to : 

https://technet.microsoft.com/en-us/library/cc739093%28v=ws.10%29.aspx?f=255&MSPPError=-2147217396   

Best Regards,

David