I have used Mailchimp for my E-mail newsletters so far, but I have now opened a Shopify store and would like to send my newsletters through Shopify instead.
I know how to import my customers email addresses but I do not know how to mark them all as subscribers.
This is a great question! If you have imported your customers from MailChimp to your Shopify store, you should be able to see the list of customers by navigating to the Customer section of the Shopify admin. In order to mark all of your customers to accept marketing, you will need to select the desired customers accounts, or select all by using the checkbox located towards the top. I took a screenshot from my test store to show you the section I am referring to:
Once you select Edit customers, you will be taken to the customer bulk editor.You can then select add tag > accepts marketing if the tag is not added towards the top of the page.