https://www.iubenda.com/en/help/5640-email-newsletter-compliance-guide and others.
other description of the requirements can be found in this google searchLegal obligations related to Newsletter content
US Law: Depending on where your customers live, specific laws relating to spam may apply. In the US, the FTC's CAN-SPAM Act sets rules for sending commercial messages, including email.
The major requirements of the CAN-SPAM Act are as follows:
Tell recipients where you're located.
You must include your valid physical postal address.