A mailing list is a list of email addresses that receive one and the same email simultaneously. When you send an e-mail message to the mailing list address, your message will be forwarded to all the email addresses on that mailing list automatically, but none of the receivers will learn who the rest of the recipients are. Generally, users have to sign up for a list, but occasionally email addresses are included manually without their owners’ consent. Depending on the specific mailing list administration software, you may also be able to include new subscribers, so people cannot sign up for a mailing list unless you approve their signup request. The mailing list option is pretty valuable if you’d like to send regular newsletters or some other sort of periodic notifications to clients, since you will have to send out just a single email message and all the mailing list subscribers will receive it momentarily. As a consequence, you won’t have to fill in many email addresses manually.