Mailing List to Customers

Wonder how those stores online handles a lot of emails for customer? They do send promo’s and emails to all their customers every week. And then I realize of course they must have something like a Mailing Lists that enables them to know to whom and where they are going to send their emails and even send important messages if they will be having sales or just plane announcements about the store. Others like a big mall or a clothing company that sends posts massages to all the people around the country if they are going to have sales or new available products that are up for a grab! It’s totally a lot less hassle for the said company if this is what they have been using. And I myself would rather just do it like that way if I really want to succeed in the business world!