Windows Outlook users can search Public Folders for the distribution list folder you want access to. Right-click on the folder and select Properties. Click to select the Outlook Address Book tab. Check the box next to Show this folder as an e-mail Address Book and click OK.
When you create or forward a message, click on the "To..." field to view the GAL. Open "Show Names from the:" and scroll to the bottom of the list. Under "Outlook Address Book", you should see the folder with the distribution list(s). Open it and select the distribution list you want to use.