Dirsize quota

The dirsize quota backend supports storage quota limits, but not messages quota limits. The current quota is calculated by finding all files in configured mail directories and summing up their sizes. This works pretty fast with mboxes, but dirsize is a really bad idea with maildirs. It will end up eating all your CPU and disk I/O.

v1.0 example

plugin {
  # 10MB quota limit
  quota = dirsize:storage=10240
}

v1.1 example

plugin {
  # 10MB quota limit
  quota = dirsize:user
  quota_rule = *:storage=10M
}