This is a question I have been asked several times and I still see it on different forums so I thought I would give you a hint about what you need to configure when you setup Exchange 2007 for both internal and external access.
In the given example I use mailmaster.local for the internal URL’s just to stress the difference between the internal and external URLs. mailmaster.se is of course the external URLs.
Set-WebServicesVirtualDirectory -Identity “CASServer\EWS (Default Web Site)” -InternalURL https://casserver.mailmaster.local/EWS/Exchange.asmx -ExternalURL https://webmail.mailmaster.se/EWS/Exchange.asmx
Set-OABVirtualDirectory -Identity “CASServer\OAB (Default Web Site)” -InternalURL https://casserver.mailmaster.local/OAB -ExternalURL https://webmail.mailmaster.se/OAB
Set-OutlookAnywhere -Server CASServer -ExternalHostname “webmail.mailmaster.se”
Set-ActiveSyncVirtualDirectory -Identity “CASServer\Microsoft-Server-ActiveSync (Default Web Site)” -ExternalURL https://webmail.mailmaster.se/Microsoft-Server-Activesync
If you use Unified Messaging this should also be configured:
Set-UMVirtualDirectory -Identity “CASServer\UnifiedMessaging (Default Web Site)” -InternalURL https://casserver.mailmaster.local/UnifiedMessaging/Service.asmx -ExternalURL https://webmail.mailmaster.se/UnifiedMessaging/Service.asmx
So to do this, just replace CASServer.mailmaster.se with the name of your CAS and webmail.mailmaster.se with your external hostname.
Yesterday the Swedish magazine IDG published a article about Windows Mobile phones. You can read it here:
http://www.idg.se/2.1085/1.193665/sakerhetsexperten-windowsmobiler-vidoppna
The short story (for those not familiar with Swedish) is that the phone is unsecure because of the fact that someone could send a text message to the phone with instructions to execute code. This was originally design for the operator to be able to send settings to the phone.
For those of you who use your Windows Mobile phone to connect to a Exchange 2007 server there are quite a lot you can do to with active sync policies:
As you see below you can block all unsigned applications from being installed into your device and if you know what applications you are facing (could be a bit tricky) you can add these as blocked.
Please note that if you want to use these advanced settings you need Enterprise CALs for your users.

A couple of months ago I wrote a blog about a problem I had with CAS, it’s in Swedish but in essence the problem is the following. If u have Exchange 2007 and you change the default active sync policy and then install a new CAS, the default policy will change back to the configuration it was before you changed it.
Today I had a long talk with some of the guys in both the Windows Mobile and the Exchangeteam and we brought up this problem and it turns out that it will soon be fixed! Great news!