A mailing list is a collection of email addresses which get the very same message simultaneously. When you send a message to the mailing list address, it will be forwarded to all the email addresses on that mailing list automatically, but none of the receivers will know who the rest of the recipients are. Generally, people have to sign up for a mailing list, but sometimes email addresses are included manually without the permission of their owners. Depending on the concrete mailing list administration software, you may also be able to add new mailing list subscribers, so users cannot subscribe to your mailing list unless you approve their signup request. The mailing list functionality is rather valuable if you would like to send newsletters on a regular basis or some other type of periodic publications to customers, considering that you will need to send only one email and all of the subscribers will receive it instantly. As a result, you won’t have to enter lots of email addresses manually.