Just a guess, as to where to start looking. With the building the new Win 2003 server, I’m assuming you installed all the latest patches updates. Are all these present on the original problematic 2003 server? There might be a permissions issue as to who can write to the server, perhaps there are some legacy aspects to your problem server 2003, was this server made from scratch or was it upgraded from an earlier version? Settings can get passed with upgrades and cause problems in newer versions. I had an exchange server that was upgraded from Exchange 5.5 to Exchange 2003 to Exchange 2007. A setting from the 5.5 version gave me three days of problems trying to get our e-mail to work with phones… Also check to see if the students are part of a group with write privileges.