I received an email with a coupon offer and viewed it within webmail (should not matter which provider).
I wanted to print my offer, but my printer was down, so I forwarded the email to a friend so he could print it for me.
My friend opened the forwarded email within his webmail. Within the email is an image that states 'click here for the offer'. Right-clicking on that image and selecting 'Copy link' within the browser results in the link to the offer being copied to the clipboard.
All is as expected... except that the link to the offer contains his email address! When I view the original email, the link contains my email address, as expected.
How is this possible?
How can an email address change itself just by being forwarded?
How can a forwarded email know the recipient's email address?
UPDATE: Thank you for the responses thus far. We repeated the steps above, this time first clearing all cookies (including flash cookies) and web history on both systems. The link in the forwarded email still knows the email address to which it has been forwarded. Interestingly, it actually enables the offer for that email address as well, assigning what looks like a new UUID as part of the offer link.
UPDATE 2: Looking at the email headers, there is an
In-Reply-To and a
References header item that each include an email address for the original sender. The
multi-part/alternative; boundary="[string]". The actual content is almost certainly HTML.