GetResponse is an advanced feature-packed autoresponder, with a well tracked affiliate program.

Two-tier program pays 30% and 10% residual commissions on all fees your referrals pay.

Tracks by cookie, by dynamically generating pages with your ID embedded in the URL, and by storing your ID in all referrals profiles, even if they sign up for a free account.

Another good feature, is when an auto-responder message is send out from a free account, it includes a small link at the bottom with your affiliate ID embedded as well.