Delivery time expiration

[Scot L. Harris]

On Mon, 2006-02-13 at 15:14 -0500, Tony Nelson wrote:

> I wonder if greylisting pays any attention to MX records?  (I just don't
> wonder enough to look for myself.)

None of the greylisting implementations I am aware of looks at MX
records.  Typically the way a smtp server farm is handled is by
whitelisting those addresses.  There are a few relatively large
organizations that are known to have such server farms.  And the
greylisting implementations I have seen deal with this by whitelisting
the servers in those server farms so there will be no delay or rejection
of the first message.  

Greylisting still works wonders since the bulk of the spam still appears
to come from non-compliant zombie hosts which just spray email and don't
bother to check any of the return codes.  In combination with
spamassassin you can achieve near 100% reduction of spam.