Go to https://arlingtonlist.org/subscribe to get to the subscription form (it will redirect you to the list software page) In the form enter
The list software will then email you a confirmation message. In that message is a link to click on to confirm your subscription. The message also mentions replying, but that is less reliable as some email programs reformat messages in ways that the list can't recognize. You will then start to receive your messages. Note that you must send message to the list form the address you subscribed with. To unsubscribe, see Unsubscribing