does anybody know how browser/emailclients work together in regards to sharing cookies?

if there is an image embedded in an html email - will some email clients send along cookies (if the browser posses them) for that domain when downloading the resource?

it seems that browser and email clients are often working tightly together. Maybe some of you guys already investigated this.

They don't share cookies. Are you talking about image tracking? That doesn't require the support of the email clients the person sending the email just sends a unique tracking token in the URL string that they associate with the email address they have on file:

joe@freemail-site.com -> 123412341234

Then they include a link that is something like:

<IMG SRC="http://www.trackingsite.com/img.jpg?123412341234">

When your browser opens the HTML tag sends the 123412341234 and the tracking site knows that joe@freemail-site.com opened the email.

- RSnake
Gotta love it. http://ha.ckers.org