Hi,For example, I know user A send an email to user B, I want to check if user B replied this email, but I don't want to go into user A or B's emailbox, how can I do this in exchange server 2007?Thank you!

Mesage tracking is the easiest way in this case.Also note the new audting features of Exchange 2007 SP2:http://technet.microsoft.com/en-us/library/ee221156.aspx

Thank you so much Andy!

Yes, you could use Message tracking. Please refer to the following articles for more information: Managing Message Tracking http://technet.microsoft.com/en-us/library/bb124375.aspx http://www.msexchange.org/tutorials/Exchange-2007-Message-Tracking-Part2.html Thanks, Elvis