Overview:
  This resource applies the standard collection item pattern to individual
  quotas email mapping rules.  ID in the resource path is formed from the
  provider type and the domain, formatted as <provider_type>:<domain_string>,
  where <provider_type> = "ad" | "local" | "nis" | "ldap".

Method GET:
  Retrieve the mapping information.


Method PUT:
  Modify the mapping.


Method DELETE:
  Delete the mapping.


