Exchange Server 2010 / Outlook 2010
My remote users connect using Forticlient either IPSEC or SSL.
These machines are not necessarily joined to the domain but in many cases are.
DNS doesn't seem to be the issue, I have even gone as far as hard coding the machine name and IP in the hosts file and never have a problem pinging the server it but it's 50/50 whether or not I can get it to resolve (underline) the account name when configuring outlook. I have similar problems when connecting using HTTP in Outlook but never have a problem going directly to the OWA client.
I am at my wits end here!