[Mailman-Users] Which user is harvesting sender emails?

[Steven D'Aprano]

On Thu, Aug 18, 2016 at 04:36:58PM -0700, Mark Sapiro wrote:
> On 08/18/2016 04:48 AM, Richard Hipp wrote:
> >
> > It would be great if there were some way to send a message where the
> >>From field of each recipient was slightly different, and different in
> > a way that was traceable back to the list member.  That would allow me
> > to identify the leaker.
> 
> 
> There are various things such as VERP and full personalization that add
> recipient specific information to the envelope sender and headers such
> as Sender:, Errors-To: and even To:, but these probably won't help.
> 
> Altering the From: based on recipient can be done by modifying the code.
> Say you have a message "From: Ann User <ann at example.com>" and you want
> to change that to "From: Ann User <ann+xxx at example.com>" where xxx is a
> unique code for each recipient.

Isn't that risky? Not all mail servers understand +xxx addresses. 
(What's the official term for that?) I know of at least one domain that 
uses -xxx instead, because they found too many broken mail servers that 
claimed that + was not legal in an email address.

The point is that if you mangle the address in this way, and people 
email Ann+xxx at example.com, there's a good chance that it won't be 
delivered.

I'd be more inclined to look at the IP address where the spam is coming 
from. Does it match one of your users? Then they are likely the culprit 
(or rather, more likely a bot on their machine is the culprit).


-- 
Steve