Noel Jones put forth on 4/8/2011 11:38 PM: > On 4/8/2011 10:57 PM, Stan Hoeppner wrote: >> email builder put forth on 4/8/2011 10:14 PM: >> >>> Or is this merely a poor-man's greylisting? >> >> In essence, yes. >> > > No, not at all. > > Greylisting breaks the connection and forces the client to reconnect > after a cool-down period before accepting mail. Greylisting has been > quite effective against spambots, but at the price of delaying mail from > legit clients. Just about all greylist implementations have some sort > of auto-whitelist function to not penalize proven good clients. > > The sleep restrictoin only delays postfix responses, does not break the > connection, and even when first invented was not particularly effective > against bots. I expect it's even less effective now, but I don't know > anyone that's tried it lately.
I was speaking to intended effect, not the physical mechanisms, i.e. both are used in an attempt to block bot spam only. It seemed this was the short answer the OP was after. -- Stan
