8 Jan
2007
8 Jan
'07
6:28 a.m.
On that note, is there zero spam from ISP servers? I'd suggest not.
Greylisting is meant to cause spam sent from non-MTAs (i.e. drones) to get deferred; they don't tend to have mechanisms to deal with 400 series deferrals. It won't do much at all for spam delivered via an Actual MTA (Corporate, ISP or otherwise) except delay it a little.