The articles describes specific of Autodiscover service implementation in POA Hosted Exchange module.
To support Autodiscover functionality for Exchange 2007/2010/2013/2016 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 to native Exchange Autodiscover directory. Optionally the custom Autodiscover filter can be installed on CAS server. For details see https://kb.odin.com/en/116228.
Autodiscover redirection with SRV-records is not yet supported by POA.
Autodiscover service, which parameters are used by the Autodiscover Redirect site, should always use an IP address and site name that differs from other services.
The following picture demonstrates how Exchange Autodiscover service is implemented in POA Hosted Exchange module.
- First of all, a client checks the local Active Directory for Autodiscover configuration. This step fails for external connections.
- A client checks Autodiscover on standard HTTPS URLs:
https://autodiscover.<smtp-address-domain>/autodiscover/autodiscover.xml. The connection to these URLs also fails, because configures special bindings on the web site with the Exchange Autodiscover virtual directory and on the web site with Autodiscover redirect.
- A client checks Autodiscover redirect on HTTP URL
- Autodiscover redirect handles this request and redirects a client to the Autodiscover virtual directory:
- A client contacts Autodiscover on the URL returned by the Autodiscover redirect.
- Autodiscover filter catches requests from native Exchange Autodiscover and changes the Autodiscover output (substitutes domain names in URLs).
- Output of Autodiscover (original or processed by filter) returns to client.