instead of DNS, stamp value server

this occurred to me quite a long time ago but I never wrote it down.

If instead of using DNS, we used a simple server (Web, XML RPC) and the 
request returned the number of bits of stamp that IP address should 
calculate in order to successfully pass the filter on the far side.

This bit server would also be a reputation server.  the number of bits 
it would return for an IP address would increase if spam came from that 
IP address and it would decrease if mostly good e-mail came from the IP 
address.

For example, if you get e-mail from an ISP and the first 10 messages 
come in with stamps and are not declared spam, the requirement for that 
ISP would drop by a bit.  If another 10 messages come in, the 
requirement drops by another bit until the maximum reduction in stamp 
size has been reached.

On the other hand, an IP address start sending you spam and after 3 
messages, you increase the required spam by a bit so forth and so on 
until they are looking at the maximum increase in stamp size.

What's interesting about this is that if you have a company sending out 
newsletters and the newsletters are voted as spam, their stamp 
requirements are now significantly increased which tells them that the 
reputation is in the dumpster.

this is what I call stamp size as a proxy for reputation.  Stamps can 
also be used as a proxy for attention in a similar way.  make a big 
enough stamp, you get through.

the same database that is used for the reputation proxy can also be used 
for a blacklist in that if the message has a bigger than average stamp 
size, it's not let through unless it has a stamp of that size.

stamps are fun to play with.

---eric