How does greylisting affect MUAs?

Gary Mills mills@cc.UManitoba.CA
Fri Oct 24 19:57:38 UTC 2003

On Thu, Oct 23, 2003 at 09:22:51PM -0600, Vernon Schryver wrote:
> > From: Gary Mills <mills@cc.UManitoba.CA>
> > > That's a good reason to whitelist for greylisting the IP addresses
> > > of those cable or DSL connected home systems.
> >
> > We don't have a record of their IP addresses.  The DSL IP addresses
> > change every day.  I don't see how this could be done.
> Good point.  I was too specific.  You need to whitelist them for
> greylist by any of the many ways including IP addresses,
> various headers, and SMTP AUTH.

That gives more latitude, but it's still awkward.
> > We could, of course, tell them to use the MSA port instead of the SMTP
> > port, or use SMTP authentication, or both of those, and exempt those
> > clients from greylisting somehow. ...
> You and they must already be doing something like that or wouldn't
> your SMTP servers would be open relays?

Yes, the home users must authenticate to relay mail, either with SMTP
authentication or POP/IMAP before SMTP.  SMTP authentication is to be
preferred, but only a few have moved to that so far.  The missing
piece in the puzzle is how to use the authentication information to
exempt them from the greylisting delay.

-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-

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