CASL
Canada's Anti-Spam Legislation — requires consent before sending most commercial electronic messages.
CASL is Canada's federal anti-spam law, in force since 2014. It's significantly stricter than CAN-SPAM: most commercial electronic messages require either express or implied consent from the recipient before sending.
Express consent means the recipient explicitly opted in (a checked box on a signup form, a written request). Implied consent is more limited — for example, a recent business relationship within 24 months, or publicly published business contact info (provided the message relates to the recipient's role). CASL also requires clear sender identification and an unsubscribe mechanism that processes within 10 business days.
Penalties are steep: up to CAD 10 million per violation for businesses, and individuals can pursue private right of action. For senders with any Canadian audience, CASL compliance shapes opt-in flow design and list-acquisition practices. Many international senders default to GDPR/CASL-compliant opt-in to avoid having to segment compliance by geography.