If a merchant has affiliates who don’t have Web sites, but they want to refer people to the merchant’s site via e-mail or offline methods, how can their referrals be tracked so they’re paid for sales?
The merchant will provide you with a unique affiliate link to use. That link will identify you as the referrer of a given sale or lead that you send over irregardless of whether you send the traffic from a Web site, e-mail, paid search, etc.
A typical affiliate link will be somewhat unmarketable offline and too long for text e-mail.
So what you might want to do is use redirects or domain forwarding to shorten your links and make them easier to remember.