Unsubscribe Functionality on Promotion Mailing

Currently, is there unsubscribe functionality that could be added to promotion mailings?

Thanks in advance

A user can log in to the site, go to "My Account" and untick "I would like to receive newsletters"

Is there a way to directly perform this without having to login?

For instance, create a link which is parametarized query using userid or some user hash?

Thanks for your help