§ 316.5 Prohibition on charging a fee or imposing other requirements on recipients who wish to opt out.
Primary source
Verbatim text below is from the Electronic Code of Federal Regulations (eCFR), a public-domain U.S. government work. Always verify the current version with the eCFR before relying on it for any legal matter.
Full Text
Neither a sender nor any person acting on behalf of a sender may require that any recipient pay any fee, provide any information other than the recipient's electronic mail address and opt-out preferences, or take any other steps except sending a reply electronic mail message or visiting a single Internet Web page, in order to:
(a) Use a return electronic mail address or other Internet-based mechanism, required by 15 U.S.C. 7704(a)(3), to submit a request not to receive future commercial electronic mail messages from a sender; or
(b) Have such a request honored as required by 15 U.S.C. 7704(a)(3)(B) and (a)(4).
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.