On Tue, 2012-07-17 at 11:19 -0400, Chris Knadle wrote: > > * Recipient address rejected: Greylisted for 2 minutes
> > ...
> > Probably DNS, RDNS or SPF issue. right or wrong ?
>
> I don't think this is RDNS or SPF is related.
It might be. Any half-sane greylisting implementation will have to have
some *reason* for greylisting the messages. Lack of reverse DNS is
certainly something that triggers greylisting on my systems.
You could also imagine people using SPF as a trigger — either an SPF
failure causing greylisting to happen, or an SPF 'pass' causing it to be
avoided. It's one of the few things that SPF might actually be useful
for.