The ISP should help them setup their mail servers to ensure they adhere to certain standards in their server configurations. That is "service". As a matter of fact, they can also enforce the use of port 587 for mail submission, which will lock our most (if not all) spam emanating from compromised hosts on their LAN.

How would a company like Safaricom, Orange or Zain enforce this for all their broadband, 3G or EDGE clients who have no mail servers since they are 'home users' and only use outlook to send emails and they have no technical knowledge so to speak.