Macintosh Manager enforces Soft Disk Quotas rather than Hard Disk Quotas.
Definitions
Soft Disk Quotas: User accounts have a fixed amount of disk space in their documents folder, which can be used for any purpose. Macintosh Manager enforces Soft Quotas by allowing the user to exceed the defined disk quota in order to save a single file. However, users are subsequently prevented from saving additional files because the quota has been exceeded.
Hard Disk Quota: This feature prevents users from exceeding their defined quotas before they can try to save a file. This is not a feature of Macintosh Manager.
Solution
Macintosh Manager administrators should periodically check user folder size to determine if quotas have been exceeded in order to prevent server volumes from becoming too full. This can be easily accomplished manually or by using Sherlock, AppleScript, or a third-party file utility.
Note: Enabling Macintosh Manager's disk quota feature and setting the value to 0 (zero) does not enforce a disk quota. Use a value of 1 or higher to enforce a disk quota.