The articles describes specific of Autodiscover service implementation in POA Hosted Exchange module.
To support Autodiscover functionality for Exchange 2007/2010/2013 POA uses configuration recommended by Microsoft in HMC 4.0/4.5 solution for Exchange 2007.
This solution is based on the special IIS redirect site which handle all Autodiscover requests and redirects them to Autodiscover service. To support this solution POA automatically registers 'autodiscover' DNS record in all domains with 'Microsoft Exchange' mail hosting service. This record points to the Autodiscover redirect site.
POA Autodiscover redirect site redirects Autodiscover requests to the special AutodiscoverProxy URL. Custom application installed in the AutodiscoverProxy virtual directory performs local connection to the Exchange Autodiscover service and substitutes domain names in Exchange Autodiscover service response with the correct branded URLs.
Autodiscover redirection with SRV-records is not yet supported by POA.
The following picture demonstrates how Exchange Autodiscover service is implemented in POA Hosted Exchange module.
1. First of all Outlook checks local Active Directory for Autodiscover configuration. This step fails for POA-managed Hosted Exchange mailboxes because customer is not located in the AD domain where Exchange is deployed.
2. Outlook checks Autodiscover service on standard HTTPS URLs:
https://<smtp-domain>/Autodiscover/Autodiscover.xmlwhere <smtp-domain> is the domain part of a mailbox a customer wants to configure Outlook for.
Connection to the URLs above also fails because POA configures special bindings on web site with Exchange Autodiscover virtual directory and on web site with Autodiscover redirect.
3. Outlook checks Autodiscover redirect on HTTP URL:
4. Autodiscover redirect site handles this request and redirects Outlook to Autodiscover Proxy virtual directory:
5. Outlook contacts Autodiscover proxy on URL returned by Autodiscover redirect website.
6. Autodiscover proxy contacts local Autodiscover service.
7. Local Autodiscover service returns mailbox settings to Autodiscover proxy.
8. Autodiscover proxy receives Autodiscover service output, substitutes domain names in URLs with correct branding URLs and returns result to Outlook.