Q: Is there an easy way to block the messenger services (especially msn messenger) at say the SBS2003 server level (ie so no client computers can connect)?
A: You can handle that by a GP and the options within the Group Policy to
either allow Messenger to work or even load as far as that goes.
Open Server Management and then Drill down to Advanced Management and then Group Policy Management and then Domains and then Your Domain Name and then Group Policy
Objects and then right click on Small Business Server Client Computer and
This will open the Policy Editor and under Computer Configuration and then Windows Components and then Windows Messenger you have 2 options there to turn off Messenger for running and or loading initially.
Also in this Policy there is a place to not allow certain Applications to run. Just add the exe for Yahoo here and this will block that from running also. This works on 2000 Pro Workstations and above.