Question:

We have 2 sites
Site 1 is the gateway to the internet and all email flows from the remote site thru the main site to the public network.
Each site has an exchange server running transport and mailbox roles
However the main site has an entry in dns for autodiscover.domain.co.uk pointing at the IP of the exchange box.

However I keep getting certitificate errors on Outlook 2007 clients. they originate from autodiscover.co.uk

We currently don t publish OWA to the internet (we  may at some point but the VPN we use works fine)
How do I get rid of these annoying errors?
Do I have to go and buy a commercial certificate?

Solution:

Whoever told you that you required two Exchange servers, was wrong.
You don’t need any kind of alias or anything.

Autodiscover internally works in a different way to external clients during the account setup phase. It is after the account creation that the problems start.

You need to deploy Exchange correctly. That means a UC/SAN certificate should be purchased, with the correct DNS records – which includes a specific autodiscover host name in the public DNS.

http://blog.sembee.co.uk/archive/2008/05/30/78.aspx

Simon.