code: function(dnsaddr) {
    var domain = getAddressDomain(dnsaddr);
    if(domain !== undefined && clients[domain] !== undefined)
      return clients[domain];
  }
docs: Get the ToxDns client for a specific address.
  @param {String} dnsaddr - Address (ex. 'user@toxme.io')
  @return {ToxDns} client to use for the given address, or undefined if none
  for the address domain