I recently migrated from exchange 2003 to 2010. Currently it is in co-existance.
I have a handful of users which i switched their mailbox to 2010. All clients are using outloook 2007.
I will try to list my setup as simple as possible.
The certs i have setup are all setup with my external DNS (mail.contoso.com).
I have also set the internal URL to see mail.contoso.com. So when outlook opens up initially, autodiscover see's mail.consoso.com and i have no cert errors, just the login dialog box.
My internal domain and external domain are different, as well as my Email alias.
For example, My internal domain is internal.contoso2.local and my Email address is firstname.lastname@example.org for autodiscovery.
What i would really like to know is how i can stop outlook from prompting a username/password when initially opening the client?