The Recurring automation sends continuously an email to your subscribers in a specified recurrence time that you choose.
You can design an email template describing your company or an introduction to your business to guide the customer through your products and services.
You insert the campaign name, the recipients, the from address, and the Email template design as you would do in a regular campaign, then get to the timing section.
See How To Set Up Campaign Recipients for the recipients section.
On the timing section of the Recurring Email Automation you have to select the time interval when the campaign will run, then you can specify if that campaign will send the emails in selected days of the week, in selected days of the month or by setting an interval of every X days.
You have to select a specified time, the email will be sent only at that particular time on the selected days (see picture above).
Then set up your desired time zone and as in regular campaigns you can turn on gradual sending and google analytics if you want to.