> > Why 53 seconds? Because when you're blocked, you'll retry in 300 > seconds. If greylisting was going to block any spam, it would > have done > so with a 2 second delay. And my users complain when mail is delayed.
A real MTA will retry in, at least, 300 sec. A bot will retry as soon as possible, if ever, because its time is valuable In two hours a bot could easily fall in a blacklist. Because the graylisting is not IP based, but the Sender-Recipient values, it will not have any side effects for customers. Choosing a long time to live and configuring good whitelists, will help with this also. > I greylist on these machines by IP address, and as I said, > greylisting > on these servers seems to only block about 1% of the spam. > I think, if it works as everyone here says, spamdyke is worth a try, because it doesn't graylist IP, but the tuple (From,To) addresses.
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