List Mail User wrote:
Certainly not (no dunce cap). Public airing of ideas generally
has merit - quite possibly this idea can be refined to something similar
that will provide a benefit (I admit, I have not given it a lot of thought).
one thing that an MTA can do is to delay its rDNS lookup until it gets
the helo name. then do a forward lookup on the helo name.
if one of the returned IPs matches the client IP, there will be no need
for the classical double lookup.
if one assumes that most helo names are correct, then this would be a
minor improvement. and the benefit is that it automatically checks for
helo validity (I don't mean one would reject the helo, but he knows if
it's good or not).
(I think iMail does something like this, but I can't say for sure).
