Author: Tor Slettnes Date: To: Bruce Richardson CC: Exim users list Subject: Re: [Exim] Greylisting + multiple MX hosts -> multiple attempts
On Mar 23, 2004, at 11:49, Bruce Richardson wrote:
> Much more difficult? Greylisting seems to assume that the programs
> used by spammers never try to resend. If greylisting becomes at all
> common, won't spammers simply adjust their programs to retry at least
> once? At which point we would be back at square one, only with
> slightly
> less efficient mail systems.
Current spamware tools typically retry right away (without waiting) --
the Greylisting white paper has some wording to the effect of flagging
IP addresses from which such repeated attempts are made as possibly
spamming hosts, to be included (temporarily) in some sort of RBL.
Spamware typically does NOT cache the mail for repeated attempts later
- doing so for thousands of recipient addresses puts too much of a
burden on the spamming machines. Spammers care about getting their
message out to as many people as possible with as little resources as
possible - if they run into any low-scale problems, they ingore them
and move on.
