On 26/10/2011 16:22, John C Klensin wrote:
Independent of what advantages it offers people who are trying to
cooperate in sending legitimate mail, to paraphrase Paul Vixie, giving
spammers the information they need to become smarter and the
incentives to do so are really not in our long-term best interests.
The reason why I don't think this is an issue, is that spammers already
have the information they need to get around greylisting. The
'retry=<time>' data won't give them any information they need to be able
to get their messages through. However, the fact is that, for now at
least, many are not doing anything about countering greylisting. When
they do decide to do something about it, the 'retry=<time>' data won't
be vital to them, or even make their job significantly easier.
Having said that, I'd prefer the 'retry=<time>' extension to be generic,
and not linked to greylisting, except by coincidence.