Depending on your location and the location of your recipients, you may need to comply with various laws. Key legal requirements include:
CAN-SPAM Act: Applicable in the United States, it requires that you don't use false or misleading header information, don't use deceptive subject lines, and include a physical address and a way to opt-out. GDPR: Applicable in the European Union, it requires explicit consent, data protection, and the right for users to access and delete their data. CASL: Canada's Anti-Spam Legislation requires express consent and includes specific content requirements.