Mailing List Message #8814
From: Bill Cole <>
Subject: Re: Checking for NO UCE in smtp banner
Date: Thu, 30 Aug 2001 19:42:30 -0400
To: SIMS Discussions <>
At 7:09 PM +1000 8/30/01, Terry Allen  imposed structure on a stream of electrons, yielding:

On Wed, Aug 29, 2001, 17:17:02 GMT
  Pete Stephenson, <> wrote:

Is there any maximum size limit in the banner? (I have no intention
of writing a novel, but I'd like to avoid breaking stuff in the
aforementioned manner.)

255 bytes - the limit for a string in an STR# resource.

Hi again,
Excuse my ignorance, but this talk of UCE banner's grabbed my
curiosity. Just what is a UCE banner? does it mean 'Unsolicited Commercial
Does adding this NO UCE banner prevent the (correctly formatted)
spam sender's mail coming into the server? If this is the case, it would
seem a very useful modification to make.

The server's  'banner' is the line it sends at initial connect time. Until the client side sees the banner, it is not supposed to send any commands. Technically only the initial 3-digit response code part of the banner is meaningful, but traditionally the remainder has included things like MTA name and version and hostname.

A very popular idea for drawing a middle line between outright banning of UCE and doing nothing in law has been to define a standard way for server owners to state their policy to anyone who wishes to offer mail to their machine. The banner is the logical way to do this and at least one of the failed federal bills in the US has included language that would have made "NO UCE" in a banner the electronic equivalent of "No Trespassing" signs on private property. (In the US, property without fences or such signs is open to rather extensive use by anyone, but with prohibitive signs trespassing, hunting, camping, etc. become criminal offenses)  A law that established this (or more likely, one which left the technical details to someone like the IETF, wehich would likely adopt a banner standard) would be hard to fight politically in the US because it is a clear endorsement of private property rights which would be exercisable in an open and transparent fashion. The spammers and their fellow-travelers really hate the idea with a passion and have worked every political trick they can find to smother any bill that comes close to this, even though it is far from what many in the anti-spam community would prefer: an outright ban on all UCE.

So far, adding special language to a banner probably has little or no impact. Spammers do not have to honor it and  so they don't bother checking. If they were smart, they would be checking now because it would at least help them avoid places where the owners of servers are announcing their enmity.
Bill Cole

Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster