William Herrin wrote:
Placing your mail server behind a NAT box and changing the NAT IP during a move does absolutely nothing to update the public and private RBLs and whitelists.
This case probably deserves more elaboration. Today, just about every email reputation system is based on the IP address of the sender. There are many such systems, including RBLs, PBLs, etc. Legitimate senders that originate large volumes of mail do not like this precisely because it takes time to develop a positive reputation. In some cases these guys end up either inheriting or even sharing IP addresses through common MTAs where their reputations are tied together.
Within the IETF we've developed DKIM that I hope will spawn reputation systems based on domain and not IP addresses. However, that is very much a speculative notion, and certainly far in the future. One reason it's speculative is that it may well be that people want to use both IP address AND domain to make their processing decisions. They can make the answer on IP address far earlier in an SMTP transaction than they can on domain, and that has its advantages.
The key point for this group is simply this: the IP address *is* an identifier, an index key, and many other things that we'll never fully know. It is possible to change, but only gradually over time. If it doesn't have to, all the better.
Eliot -- to unsubscribe send a message to rrg-request@psg.com with the word 'unsubscribe' in a single line as the message text body. archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg