
In most businesses there is a request for a Director/Manager to be able to check his email remotely. More times than not he wants it on his PC @ home, mobile phone and the ability to access it anywhere in the world. Those with a Small Business Server operating system have this luxury from day 1. However in Exchange 2010 its not an “out of the box” solution. However since OWA is, half the work is already done for you. So i set about enabling my “users” to access email from their domain laptops in Outlook using a single sign-on.
Step 1: Install and SSL Cert for your remote site.
Step 2: Enable Outlook Anywhere in Exchange.
Enable-OutlookAnywhere -Server ‘SERVERNAME’ -ExternalHostname ‘mail.externaldomain.com’-DefaultAuthenticationMethod ‘Basic’ -SSLOffloading $falseFor the GUI method click here
Step 3: Install the Windows RPC Over HTTP Proxy Component
For Outlook Anywhere to work correctly, the Windows RPC over HTTP Proxy component must be installed on your Microsoft Exchange Server 2010 server that’s running Windows Server 2008 (R2). So i install this new role, quick reboot and hey presto outlook works. At this point you can stop and continue to use Basic mode. However for NTLM you need to change the setting in Part 3.
Step 4: Set Outlook Anywhere to NTLM Authentication
Disable-OutlookAnywhere -Server ‘SERVERNAME’(then press Y to confirm)Enable-OutlookAnywhere -Server ‘SERVERNAME’ -ExternalHostname ‘mail.externaldomain.com” -DefaultAuthenticationMethod ‘NTLM’ -SSLOffloading $false
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Wait the required 15 Min’s and it will work. This is extremely beneficial as the user does not have to authenticate with his/her user name and password each time. Given that it also requires the user to type the domain name as a prefix “DOMAIN\Username” NTLM allows you to rule out that horrible explanation into “why you have to type the domain name” where the answer is inevitably, “you just do”.
Resources: Outlook Anywhere Howto http://technet.microsoft.com/en-us/library/bb123542(EXCHG.140).aspx Enable NTLM Authentication http://technet.microsoft.com/en-us/library/dd776122(EXCHG.140).aspx

Heres some more information that might be helpfull,
Exchange 2010 – Setup and Deploy Outlook Anywhere
Pete