'Add a domain for which the service will accept email.
@type name: L{bytes}
@param name: A domain name.
@type domain: L{IDomain} provider
@param domain: A domain object.'

def addDomain(self, name, domain):

    portal = Portal(domain)
    map(portal.registerChecker, domain.getCredentialsCheckers())
    self.domains[name] = domain
    self.portals[name] = portal
    if (self.aliases and IAliasableDomain.providedBy(domain)):
        domain.setAliasGroup(self.aliases)
