Is it possible to detect if an email newsletter has been forwarded?

Lonnie Olson lists at
Wed Feb 6 13:43:13 MST 2013

In a web request you also have access to the User Agent info.  You can
combine this with the IP to get a pretty close approximation to a
single user.  Subsequent clicks from different IP and/or User Agent
will likely be a different person.  Though not foolproof, it's closer
than IP only.

On Wed, Feb 6, 2013 at 1:10 PM, Ken Snyder <kendsnyder at> wrote:
> We have an email newsletter that includes a tracking image, plus each link
> contains a hash so that we know which recipients opened the email and who
> clicked on what link.
> The client is asking if it is possible to detect a) if that newsletter has
> been forwarded to someone else, b) if that new recipient opens the email,
> and c) if that new recipient clicks on the links.
> My only thought is that we could make a loose inference of second-hand
> opens and clicks by tracking the IP Address of each open and click. E.g. if
> there are two clicks from two different IP Addresses it *could be* another
> person.
> Is there any other way to detect second-hand opens and clicks?
> Thanks,
> Ken Snyder
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