** Delete existing mail domains.
** Rename existing mail domains?
** Lock a mail domain (until the customer has paid its bill for example)
** Individual number (from zero to infinite) of mail accounts per mail domain.
* Mail Domain Alias
** Rename existing mail accounts
** Get used and available Quota of mail accounts
** Lock a mail account (until the customer has paid its bill for example)
** Change owner of existing mail accounts.
** Mail account sizes starting from 100 Megabytes (no upper limit). The size is enforced with a soft quota and a hard quota. The mail accounts can be enlarged by 100 Megabyte steps.