Email Marketing Question:

The CAN-SPAM Act spells out the rules for email marketers, whether their intentions are good or bad. If you're sending emails for commercial use, you have to do the following:

Include an unsubscribe method.
Actually unsubscribe someone when they request it, and do it in a timely manner.
If sending for commercial uses, you need to include a physical address.
While not explicitly banned, sending to people who have not opted in is discouraged.