CASL (Canada's Anti-Spam Legislation) is a Canadian law that came into effect on July 1, 2014, designed to protect consumers from unsolicited electronic communications and to promote the use of electronic messaging in a way that fosters consumer confidence. In the context of email marketing, CASL imposes several key requirements:

1. Consent: Explicit or implied consent must be obtained from recipients before sending commercial electronic messages (CEMs). Explicit consent requires a clear affirmative action from the recipient, while implied consent can be based on existing business relationships or shared contact information.
2. Identification: All CEMs must clearly identify the sender and include accurate contact information, such as the sender’s name, business name, and a physical mailing address. If the message is sent on behalf of another organization, that organization must also be identified.
3. Unsubscribe Mechanism: Every CEM must include a clear and simple way for recipients to unsubscribe from future emails. Unsubscribe requests must be processed without delay, and no later than 10 business days after the request is received.
4. Content Requirements: CEMs must not contain misleading or false information in the subject line, sender information, or message content. They must be truthful and transparent in their communication.
5. Record Keeping: Marketers must keep records of consent, including how and when it was obtained, to demonstrate compliance with CASL if required.

Compliance with CASL is essential for businesses conducting email marketing in or to recipients in Canada. Violations can result in significant penalties, including fines and legal action. Ensuring adherence to CASL helps maintain trust with consumers and promotes ethical email marketing practices.