Co-registration is a way of buying targeted subscribers and leads to your newsletter/ezine from a
3rd party service on an individual basis.
The leads are gathered by websites who are offering something in return for people opting in to that
web sites newsletter.
It basically involves having your subscription offer listed alongside other publications offers, so that
when someone signs up to the other newsletters, he or she is given the option of signing up for
yours as well without needing to re-enter any personal information.
The reason I recommend using co-registration to build your list is because it easy, quick and cost-
effective. It is also highly targeted, because you only pay when the person joins your list and sees
your offer and the value your providing.