This is a non-friendly reminder to all startups and marketing people. If you are sending me an email and it does not have an unsubscribe link that meets the following rule (as of 2008 FTC ruling on CAN-SPAM act of 2003) then you are breaking the law:
to submit a valid opt-out request, a recipient cannot be
required to pay a fee, provide information other than his or her email address and opt-out
preferences, or take any steps other than sending a reply email message or visiting a single page
on an Internet website
source: http://www.ftc.gov/os/2008/05/R411008frn.pdf
Note: if you are not telling me about a financial transaction we made, our email is not transactional and STILL must follow that ruling.