Following CAN SPAM isn't enough to reach the inbox
One of the top entries on the list of things deliverability folks hear all the time is, “But my mail is all CAN SPAM compliant!” The thing is… no one handling inbound mail really cares. Seriously. CAN SPAM is a law that is little more than don’t lie, don’t hide, and heed the no. Even more importantly, the law itself states that there is no obligation for ISPs to deliver CAN SPAM compliant mail.
15 U.S.C. § 7707(8)(c)
NO EFFECT ON POLICIES OF PROVIDERS OF INTERNET ACCESS SERVICE.—Nothing in this Act shall be construed to have any effect on the lawfulness or unlawfulness, under any other provision of law, of the adoption, implementation, or enforcement by a provider of Internet access service of a policy of declining to transmit, route, relay, handle, or store certain types of electronic mail messages.
Many companies do list on their postmaster pages that they expect senders to comply with the law. (AOL, Yahoo, Microsoft). But just because email complies with CAN SPAM doesn’t mean it will be accepted or delivered.
Complying with the law is the bare minimum. And the way CAN SPAM is written it’s such a low bar it may as well be lying on the ground. Everyone sending unsolicited mail should be complying with CAN SPAM. But don’t expect the compliance to win you a path to the inbox. That’s just not how it works.