VERPing and Personalization (was Re: [TriLUG] Iptables help)

[Jeremy Portzer]

On Wed, 2004-03-24 at 13:54, Tanner Lovelace wrote:
> Jeremy Portzer said the following on 3/24/04 1:47 PM:
> > 
> > 
> > What Magnus was referring to is the ability with some list managers,
> > just as djb's EZLM, to set up VERP where every single message has a
> > different identifier.  So messages from trilug might have an envelope
> > sender of something like,
> > "trilug-message-34233-jeremyp=pobox.com at trilug.org" (made up syntax, but
> > you get the idea).  This causes problems with "graylist" spam detection
> > (called auto-whitelist in SpamAssassin) that might keep track of things
> > based on envelope sender.  It isn't a problem if the envelope sender is
> > the same thing for each message, which is how mailman does it.  So we
> > shouldn't need to worry if we enable VERP for normal postings in
> > mailman.

> Good description Jeremy, but let's deal with non made up examples.

Well, since we don't run EZML or similar software, I had to make it up.

> Here's an the Sender header from a message I sent while
> mailman's "Personalization" was turned on:
> 
> Sender: trilug-bounces+lovelace=wayfarer.org at trilug.org
> 
> Here is the Sender header from your message (with mailman's
> "Personalization" turned off):
> 
> Sender: trilug-bounces at trilug.org
> 
> So, it looks like to me that yes, it is changing the sender header
> and it will affect things like Mangus is talking about.  What am
> I missing here?  

The sender is still the same for every message from the list to you. 
Therefore, subsequent messages will be grouped under the same database
entry in graylists (or autowhitelists, whatever you want to call them). 
This won't cause any problems.

> Is it the fact that the sender will still be the
> same for all messages to a given subscriber even though it includes
> the e-mail address of the recepient in it? (i.e. mailman can use
> VERP to figure out who's bouncing, but not which message bounced?)
> 

Yes, that's it.  All messages from the list to a given subscriber will
have the same envelope sender for that subscriber.  The alternative,
which mailman does NOT do, which is why my example is made up, is to
include the message number (or some other identifier for the message),
AND the e-mail address, both encoded in the envelope sender.  This means
that a different envelope sender will appear in every message, even to
the same subscriber.  This will cause the autowhitelist function in spam
software to be useless, as it cannot group information by sender.

--Jeremy

-- 
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| Jeremy Portzer        jeremyp at pobox.com      trilug.org/~jeremy     |
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