When quotas are enforced on a print queue hosted on Mac OS X 10.4 Server, users don't receive any notification when they exceed their print quota. The job, or part of the job, will fail to print without reporting any error to the user. The reason for the failure will appear in the server's logs.
To verify that a print failure occurred because the user exceeded his or her quota, check the /var/log/cups/error_log on the server. You can view this log in Server Admin:
You can reset this user's print quota in Workgroup Manager: