Wednesday 27 May 2015

Microsoft Exchange Autodiscover Process Flow

I think the actual process of how the autodiscover process is often overlooked - simply because "it just works", by adding an A or CNAME such as and pointing it to our mailbox server the process is done.

Although a client - whether it be an activesync device or an Outlook client firstly looks for the autodiscover configuration in the following order:

- Firstly tries POST request to:
- If fails tries POST request to:
- If fails tries GET request (to check for a redirect):
- If fails tries a DNS SRV lookup on: which returns
- Proceeds by sending POST to:
- POST Request is successful.

Benifits of using a SRV record instead of an A or CNAME record are that you do not have to have a dedicated IP / SSL certficate for the autodiscover subdomain - but on the other hand using a SAN certifcate should mitigate this problem in the first place.


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