Autodiscover can be a lengthy process, especially if you are in a hosted environment or if your mailbox is in Office 365.
The autodiscover process consists of five different steps, it depends on your environment where autodiscover stops and returns the information. Autodiscover is using the following mechanisms:
- Service Connection Point (SCP) in Active Directory. This is used by domain clients.
- Root domain discovery, used by non domain joined clients or clients not being able to access Active Directory. All other steps are used by these clients as well.
- Autodiscover.contoso.com (standard autodiscover mechanism)
- Autodiscover redirect to autodiscover site (often used by hosting companies)
- Autodiscover SRV records in DNS (sometimes used by hosting companies)
- Autodiscover redirect to Office 365 (outlook.com)
If your mailbox is in Office 365, outlook will go through all these steps until it finds the information in Office 365. All steps will fail with the accompanying time-out and this will take quite some time. This can be seen in the Outlook Test Email AutoConfiguration option:
It is possible to disable certain autodiscover steps by creating DWORD entries in the HKEY_CURRENT_USER\Software\Microsoft\Office\<version>\Outlook\AutoDiscover registry key.
Note. <version> can be 16.0 for Outlook 2016, 15.0 for Outlook 2013 and 14.0 for Outlook 2010.
The following DWORD entries can be created:
- ExcludeLastKnownGoodURL (Outlook 2010 version 14.0.7140.5001 and later)
- ExcludeExplicitO365Endpoint (Outlook 2016 version 16.0.6741.2017 and later)
To skip the SCP, root domain and autodiscover domain check (in an Office 365 scenario) you can add the ExcludeScpLookup, ExcludeHttpsRootDomain and ExcludeHttpsAutodiscoverDomain DWORD entries and set the value to (1) as shown in the following screenshot:
After a restart of Outlook you can run the Test Email AutoConfiguration tool again to see the improved results as can be seen in the following screenshot:
This way you can exclude certain steps in the autodiscover process and therefore speed up the process (and improve user experience )
More information can be found on the Unexpected Autodiscover behavior when you have registry settings under the \Autodiscover key on Microsoft Technet.