Eliminate certificate warning when users access Outlook/Exchange 2010 on split domain setup

I have an internally-hosted Exchange 2010 Server with an internal domain, EXCHANGE0.COMPANY.COM.

I have configured all users to access Outlook (even internally) using Outlook-over-HTTP. To do so I have set up a client access certificate for the externally-facing domain mail.company.com.

The problem is that whenever users open Outlook they are promptly greeted by certificate warnings of the mismatch between mail.company.com and EXCHANGE0.COMPANY.COM. I would like to eliminate these warnings and I feel there is a way to do so either through DNS or through Exchange. I am just not sure what to do.

AutoDiscover is configured using the SRV method if that matters at all.

EDIT: Configuration on clients looks as follows

Exchange Server: EXCHANGE0.COMPANY.COM Connect using Outlook Anywhere (HTTP): on fast and slow connections, connect to mail.company.com and only trust msstd:mail.company.com

Name on certificate is mail.company.com, but Outlook was expecting EXCHANGE0.COMPANY.COM

Solution 1:

You can take care of this problem by setting the InternalURL attributes for the various Exchange components to match your external name (mail.company.com). Once you've done that you can create a DNS record (probably a CNAME for "mail.company.com" to "exchange0.company.com"-- it sounds like you named your AD domain the same as your real Internet domain name) so that clients can connect to "mail.company.com" and get directed to the Exchange Server computer.

The "set" commands for each component you'll need to run are below. You can use the "Get-" versions of these commands to see how they're set now.

Set-ActiveSyncVirtualDirectory -InternalURL
Set-AutodiscoverVirtualDirectory -InternalURL
Set-ClientAccessServer -AutodiscoverServiceInternalUri
Set-ECPVirtualDirectory -InternalURL
Set-OABVirtualDirectory -InternalURL
Set-OWAVirtualDirectory -InternalURL
Set-WebservicesVirtualDirectory -InternalURL