You would need to convince your ISP to allow you to modify your PTR. There are many servers that implement one form or another of the S25R methodology [1]. Th

You would need to convince your ISP to allow you to modify your PTR. There are many servers that implement one form or another of the S25R methodology [1]. That is, simple regex against your FCrDNS to see if you are a generic network device or generic home user. The page I am linking to is an example of the concept, but many anti-spam tools implement this in varying degrees. [1] - http://www.gabacho-net.jp/en/anti-spam/anti-spam-system.html http://www.gabacho-net.jp/en/anti-spam/anti-spam-system.html