Quota limit rules are used to govern the amount of disk space and the number of files users can upload to their home folders. Quota limit rules prevent a user from performing an action that would cause the limits specified in the rule to be exceeded.
Unlike failed login rules and folder action rules, which send notifications when the rule is triggered, quota limit rules can be configured to send notifications as a warning prior to the absolute limit being reached. For example, a quota limit rule that specifies a limit of 20 MB in the home folder can be configured to also send notifications as a warning when the size of the user's home folder reaches 18 MB.
If your users have the WS_FTP Professional client, the FTP and SSH servers can send the user's remaining disk space to the FTP client, which will display the data at the bottom of the remote file list. When you create a Quota Limit Rule, this functionality is enabled.