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: