check to see if they have subscribed all ready

Hi All,
How can I confirm whether or not a user has subscribed to my service before, at the moment I use the IP address which works fine if your on a fixed IP however if your on dialup this is flawed. Any Ideas of what I can do?

Many thanks
Chrisio :wave:

You could use cookies - but these are not reliable as the user can delete them.

if you use their e-mail address, this is much more reliable.

You have to use cookies to automatically detect whether they are signed up or not. If they delete the cookie, you have to make them sign in again, however.