most email clients (both web based and applications) block images by default. If it is web based, then the referer will be revealed and they will surely know that you are email marketting, which is against the rules on many affiliate networks and sometimes specific offers.

I have not done much testing on application based email clients, but i know the big ones outlook/outlook express block any kind of images and in alot of cases html content in general.

because of all the clients blocking images by default, its probably a huge waste of time.

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