3.1.4 Higher-Layer Triggered Events
When an Autodiscover client is configuring itself to access a user's mailbox, it sends an HTTP POST request that contains an Autodiscover request, as specified in section 2.2.3. The client waits for a response and processes the response as specified in section 3.1.5.
If the client supports the Messaging Application Programming Interface (MAPI) Extensions for HTTP, as specified in [MS-OXCMAPIHTTP], it SHOULD include an X-MapiHttpCapability header (section 126.96.36.199) in the Autodiscover request. If the client does not support the Messaging Application Programming Interface (MAPI) Extensions for HTTP, it MUST NOT include an X-MapiHttpCapability header in the Autodiscover request.