The Filer sends traps such as "Soft block limit exceeded for user 3325, tree 1 on volume students." but there doesn't seem to be any correlation/pattern as to what "tree 1" is, exactly.
What software do you use to receive such traps?
1) The "qtree status" command in ONTAP 6.4 has a -i option that will show you the tree ids for the qtrees.
2) In the NOW site, in the Tools&Utilities section, you can find a "trap listener" application specifically written to support the better quota traps in ONTAP 6.4, and do things like send email alerts. Look for "Trapnotify" on the Tools&Utilities page.
...Tim...