Greylisting -- Was: Anti Spam

Ted Mittelstaedt tedm at
Mon Apr 30 08:35:23 UTC 2007

> -----Original Message-----
> From: John Levine [mailto:johnl at]
> Sent: Sunday, April 29, 2007 6:31 AM
> To: freebsd-questions at
> Cc: tedm at
> Subject: Re: Greylisting -- Was: Anti Spam
> >> Email is not an instant messaging system, no matter how much you want
> >> it to be one.
> >
> >Cell phone companies won't take pages any other way no matter
> how much you
> >want them to.
> This might be a good time to learn about outfits like
> that provide SMS gateway service.  They charge about 10 cents a
> message.

Your still not getting the point.  The monitoring system speaks
e-mail.  If it speaks e-mail to the cell carrier and the cell carrier
starts greylisting it is screwed.  If it speaks e-mail to the SMS
gateway service and the gateway service starts greylisting it is
still screwed.

Instead of "monitoring system" substitute one of many, many, many
other embedded devices that use e-mail to send notifications.  For
example, print servers, UPSes, ethernet-to-ethernet hardware routers,

I don't understand why people are focusing on trying to redesign
the monitoring system I'm using.  Don't you have any imagination
at all?  The point was that there are legitimate situations where
the delays introduced by greylisting are a problem.  I used the
monitoring system as an example to make it easy to grasp the
point.  If it would help, I'll stop talking about it and use another

Sure, it's possible to modify the greylist to whitelist.  That
implies that the sender knows greylisting is happening, knows
how to get the recipient to whitelist, it implies the recipient
is even willing to whitelist,  etc.

Imagine a cell company that puts in greylisting being deluged by
30% of their million-plus userbase requesting to be whitelisted
for just the reason I cited.  Do you think it would be realistic
for the cell company to do this?

Sure it's also possible to do something like reconfigure the monitoring
system to just call a page-only number that goes to a pager and
use touch tones to put in a message, then to wear a pager instead of
the cell phone.  There are workarounds to the monitoring scenario
I cited.  That does not prove there are workarounds to every one
of these kinds of scenarios.


More information about the freebsd-questions mailing list