I'm sorry I didn't define the term in my original answer. Co-registration means
subscribing to one or several e-zines (e-mail newsletters) at once that are
offered to you, usually in a pop-under box that appears upon leaving a website.
Some co-registration systems work something like banner sharing schemes of
old. You sign up with a company to include a snippet of JavaScript code on each
of your webpages that causes a pop-under window to appear any time a visitor
leaves your website. The pop-under window contains a subscription form that
allows your visitors to opt in to one or more of the eight e-zines (e-mail newsletters)
listed in the pop-under, thus "co-registering" or subscribing them to several
e-zines at once. For your cooperation in displaying the pop-under, your e-zine
is listed as one of the eight e-zines in proportion to the number of times the
pop-up appears on your site. The owner of the co-registration system is compensated
by controlling one or more of the eight sign-up slots, building his own list
or selling subscriptions to companies that want to build their subscriber lists
on a pay-per-subscription basis. I don't use such a co-registration system for
the reasons stated in my previous
answer (www.doctorebiz.com/v7/030625.htm).