Email submits and zip submits come from alot of different various companies and networks. I have quite a few on my network which we get directly.
If you don't have your own network most advertisers will not deal directly. And if they do, your rate per lead will be drastically cut.
What I've seen copeac do is they just use other networks.
Look for the redirect when you use their link and you'll find some trusted networks.
I've generated over 35k on Copeac then invested about 10k of it into my own advertising network. It already payed off. =)