My company is using an Exchange Hosting provider; MailStreet per my recommendation. MailStreet offers Exchange 2003 hosting along with OWA use. Ran a pilot for a few months which went well. During pilot, when using OWA and creating a new message, users could type a few letters of someone in our Global Address List, type the message and send it and OWA would pop up the Check Names dialogue with the matches. Worked close to how Outlook works. I was pleaseantly surprised.
Now, on the new domain which lies on a different Exhange server, when the user clicks send, the Check Names dialogue comes up, but there are no names in the list even though it should get a match from our global address list.