Mailing list members are people that have registered for a given mailing list to receive regular emails, including weekly newsletters. If the mailing list client program that is used to administer the list allows it, you can also add members manually, but in this case such emails may be regarded as unsolicited and reported as spam by the users. Generally, these mailing list members can unsubscribe from a mailing list by clicking on a hyperlink in the email messages they get, or you, as the mailing list admin, can delete them manually if they request this or if you decide that some of the members should not belong to the list anymore. Each member will be able to view only their own address in the "To" field of the messages they receive, but not the email addresses of the rest of the members of the mailing list.