Every established business has lots of customers and potential customers to keep happy and in the know. Have a deal or an announcement about the business? The best way to share these things outside of social media is an email campaign.
Digital Marketing has a dedicated arm to email campaigns. You can announce things about your business and best yet, you can direct viewers to go to specific social media pages or certain pages of your website. All of the website visitors that signed up for your newsletter should be getting periodic emails from you with information, deals, and announcements. This keeps the user engaged and creates value with them. With value, comes trust and that end game is a sale.