adding an opt-out function to a mailing list application

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I want to add the opt-out function to the clients who will receive the mails. I'm a php n00b, so the best way I could figure is to send them a link to a form, where they will write their email, so I can take it out of the database via a query when they submit it. Is there a more elegant way? How can I take the user out of the database by him simply clicking on the opt-out link?