If you’re emailing your newsletter, you have a responsibility to adhere to the U.S. CAN SPAM laws.
The original law, attempting to reduce unwanted and offensive email, went into effect in January 2004. Among other things, it says you must:
1. Use a subject line that reflects the content of your email;
2. Provide recipients an easy way to opt out or unsubscribe
3. Include a legitimate postal address. (Very few artists are in the habit of doing this.)
Check out this site for more details. And keep abreast of any new legislation that might affect you.