Some e-mail programs, notably Gmail, don't deliver to you a copy of a message you send to the list, because . . .  well, because they think it's a good idea. However, you can set your preferences for the E-mail list to send you a separate e-mail acknowledging receipt of your message by the list. This setting is "on" by default; if you want to turn it off you can do so in your preferences, to which a link is found in the footer of each message from the list.