'@type service: L{MailService}
@param service: An email service.
@type root: L{bytes}
@param root: The maildir root directory.
@type postmaster: L{bool}
@param postmaster: A flag indicating whether non-existent addresses
should be forwarded to the postmaster (C{True}) or
bounced (C{False}).'

def __init__(self, service, root, postmaster=0):

    AbstractMaildirDomain.__init__(self, service, root)
    dbm = os.path.join(root, 'passwd')
    if (not os.path.exists(dbm)):
        os.makedirs(dbm)
    self.dbm = dirdbm.open(dbm)
    self.postmaster = postmaster
