Bulk Account Inviter
You can use the Bulk Account Inviter app to invite your customers to activate their accounts for your online store. This app is useful after you have imported customer accounts from another platform or from another Shopify store.
Before you begin
You need to have a customer group that contains the customers that you want to invite. See Create customer groups.
Invite customers to create accounts
To invite customers to create accounts for your online store:
From your Shopify admin, open the Bulk Account Inviter app.
In the Customer group drop-down, choose the customer group that you want to invite.
Click Create Email: By default, your invites will be generated from your Account invite notification template. If you want to change the subject or message of these invites, then edit the Subject and Message fields.
Choose an email address from the email drop-down list. This is the email address that your customers will see when they receive the invitation.
Click Review and then click Send email.
The email invitations are sent. Depending upon the number of customers that you invite, it can take a while for all the invitations to be sent.