If you make use of a mailing list to contact some or all of the users/visitors on your web site on a periodic basis, its subscribers are frequently referred to as mailing list members. They need to sign up and to express their explicit consent to get automatic emails. You can approve mailing list members manually as well, on the condition that the mailing list client software that you make use of to manage the mailing list permits this. As per the generally accepted policies, a mailing list member should be able to unsubscribe at any time. You, being the administrator, can also remove members in case they should not receive email messages for some reason. The emails that each member receives will have just one single address in the "To" section, not the addresses of all the mailing list members.