FTC Issues CAN-SPAM Act Guidanace
"If you send e-mail messages to customers and prospective customers, you should take note of the new Federal Trade Commission guidelines implementing the federal CAN-SPAM law which became effective on January 1, 2004. These guidelines attempt to clarify what is commercial e-mail, and therefore subject to the Act’s requirements, by defining when the "primary purpose" of an email is commercial. The regulations took effect on March 28, 2005...
CAN-SPAM (the "Act") regulates commercial electronic mail messages ("Commercial e-Mail") which the Act defines to mean any e-mail message whose "primary purpose" is the commercial advertisement or promotion of a commercial product or service. For e-mails falling within this category, the Act requires, among other things, that e-mail recipients be provided a clear and conspicuous notice of the opportunity to opt-out by return e-mail (or other Internet mechanism) of receiving further communications from the sender, and the sender must comply with this request within ten business days of receipt."
Read more in this Pillsbury Winthrop article from Mondaq.