Coupon Carrier keeps track of existing codes that have been added to a email address. If a code has already been assigned to a email address it will be skipped. We do this to prevent misuse where people unsubscribe and then resubscribe to a list to receive new codes. If you use gmail you can use their alias feature to create test addresses. You can receive messages sent to firstname.lastname@example.org. For example, messages sent to email@example.com are delivered to firstname.lastname@example.org.