A mailing list is a list of email addresses that get the exact same email simultaneously. When you send an email to the mailing list address, your message will be re-sent to all the email addresses on that mailing list automatically, but none of the receivers will learn who the other recipients are. Generally, people have to sign up for a list, but sometimes email addresses are added manually without the permission of their owners. Depending on the concrete list management software, you may also be able to include new mailing list subscribers, so users will not be able to sign up for a mailing list unless you authorize their signup request. The mailing list functionality is rather handy if you wish to send newsletters on a regular basis or some other type of periodic announcements to clients, considering that you will need to send out a single e-mail message and all the subscribers will receive it momentarily. As a result, you won’t need to fill in a lot of mailboxes manually.