Some stats from the graylist daemon [1]. I'm automatically accepting emails from Yahoo [2], AOL (America Online) [3] and BellSouth [4], plus three other servers that run problematic mailing lists—all other emails are going through the graylisting process [5]. I've been running the daemon for almost 48 hours, with an embargo time of one hour, and cleaning out records that haven't seen activity for 12 hours (I check this every five minutes).
Table: Current Graylist statistics tuples 2684 graylisted 8217 whitelisted 22 graylist expired 5533 whitelist expired 0
About 0.3% of all emails that are subjected to the graylist process make it through to the whitelist. Of those 22 that got through, eight were spam (amazing! Spammers using a real SMTP server!) and of those, four were delivered to an actual in-use email address.
Not bad, considering I was averaging a few hundred (maybe even as high as a thousand) per day.
Another interesting bit—I limit the size of email addresses to 108 characters and so far, only one address has been truncated, yet still made it to the whitelist (it was a notification from Linked In [6]) in 2½ hours despite coming from four different IP addresses.
It appears to be working rather well, although I do have some notes about stuff I'd like to add:
Next up—getting this implemented on one of The Company's domains.
[5] http://projects.puremagic.com/greylisting/whitepaper.html