3.2.5 Message Processing Events and Sequencing Rules
The server SHOULD validate the body of the HTTP POST request, ensuring that it is a valid Autodiscover request as specified in section 2.2.3.
If the server needs to redirect the Autodiscover client to another URL, it SHOULD send a 302 Redirect response with the Location header set to the new URL. Alternatively, it MAY send an Autodiscover response (as specified in section 2.2.4) with a RedirectUrl element (section 220.127.116.11.1.2.9) value set to the new URL.
If the server needs to redirect the Autodiscover client to another email address, it SHOULD send an Autodiscover response with a RedirectAddr element (section 18.104.22.168.1.2.8) value set to the new email address.
If the server encounters an error, it SHOULD send an Autodiscover response with an Error element (section 22.214.171.124.1.3). It SHOULD set the value of the ErrorCode element to one of the values in the table in section 126.96.36.199.1.3.2, but MAY use a value not in the table.
If the server does not need to redirect the request and encounters no errors, it MUST return an Autodiscover response with a User element (section 188.8.131.52.1.1) containing information about the user represented by the email address in the EMailAddress element (section 184.108.40.206.1.2) of the request and an Account element (section 220.127.116.11.1.2) containing configuration information for the user's mailbox.