Re: [apps-discuss] draft-santos-smtpgrey-02: SMTP Service Extension for Greylisting Operations

["John Levine" <[e-mail]>]

>I don't think this is an argument for or against standardization, however. The
>overarching goal of improving timely delivery of mail trumps the cost of
>dealing with the obsessions some sites have. IMO this protocol needs to be
>assessed almost entirely on the basis of whether or not it improves the
>situation surrounding greylisting.

In my experience, the amount of real mail that is delayed at all by a
reasonable greylister is insignificant.

Once you know that an IP has successfully retried, there's no point in
further greylisting, so you add it to the greylist whitelist (pale
grey list?)  This means that the only non-bot mail that gets
greylisted is the first one or two from an IP that hasn't sent mail
before, and that just isn't very many IPs or very much mail.  It's
certainly not worth a new SMTP extension and extra state in mail
servers.

I realize there are extreme greylisters that greylist everything on
the theory that a mail server might be sharing its IP with a bot, or
if they wait long enough the sender will show up on a blacklist, or
something.  That's certainly not a basis to standardize anything.

R's,
John