I've lost count of the number of posts I've seen by people who can't figure out how to unsubscribe. On some lists, you'll be roundly mocked for doing it wrong. Create a separate folder for list-related mail and filter those messages directly to that folder. Many mailing lists have designated subject tags that will allow you to easily set up an appropriate filter. Use the list.
Most mailing lists are an excellent way to learn from the experience of others.
But as in so many things, you only get out as much as you put in. Be willing to take the time to answer questions or engage in discussions. You'll find that doing so broadens your own base of knowledge, and may actually help in your business development. This is where your advertising text would go. You can have up to 50 words of text per ad.