Freddie here from the Shopify Support team, happy to help.
Your customers will not receive an automatic email after they put in their email address on your password page. What it will do, is create a customer profile for them in your Customers section, where you can then go and send them an email to get them to create a customer account on your store and you can begin to send marketing emails to them.
To see all of the customers who have entered in their email address, you will want to go to the Customers section of your Shopify admin, and click into each customer profile that you see here and click on "Send Account Invite," where you can enter in a custom message to your customer and send them the email. You can do this closer to the launch date of your store if you'd like, as many merchants like to do that to include the launch date and to help drive the customers to shop from you.
In case you are new to the world of email marketing, here is an extremely helpful guide that you can look into on this topic, to help you in getting started so you can become an expert at this to drive sales!
I hope this information helps, but let me know if you have any further questions!
Shopify Support - firstname.lastname@example.org
Is there any app or way to send an automatic email to customers who input their email on the password page? I would like for them to get an automatic, instant reply to their inbox when they sign up to be notified about a launch as well as future updates. I feel like this creates an instant relationship/trust build... would love some help here.