Newsletter subscription vs Registration

I'd like to have an easy Newsletter subscription box on my site. The user types his email, clicks "Subscribe" and he is done. The problem is that the site has Registration too. How should I solve the registration when the user is subscribed? I do have his/her email address (from Newsletter subscribtion) but I don't know if it is his/her.

I don't want to force the users to Register if they want only to subscribe to the newsletter list.

Should I have 2 email lists for Newsletter subscribers and Registered users and then check d开发者_开发百科uplex emails and send the newsletter only 1x?

If a user signs up for a newsletter but is not a registered member of your website, but later on decides to register, you can do a DB check upon registering them to see if they are subscribed to any newsletters, and if they are, set a 'SubscribedToNewsletter' column to true.

Or, if a registered user decides to sign up for a newsletter, simply set the DB Column 'SubscribedToNewsletter' to true.

If your email client allows groups of contacts you could make two separate groups of contacts. If one of the newsletter people decides to register, they're name should pop up from the newsletter contacts and you can just move it to the registered. Hopefully that should keep you from sending out duplicates each time.