chopp An email sending app should have a detailed statistic: when, for whom, which email was sent, did he opened, clicked, deleted, whatever...
I attached an example from my app (Klaviyo).
Two types of emails are normally in e-commerce:
1. mandatory: for example, order placed, shipping sent, etc. This kind of email you cannot send with an app. Shopify will do. Period. What you can do, change the format a bit... Actually, the customer cannot unsubscribe from these emails (there isn't any "unsubscribe" button there). That's why you cannot disable them in Shopify.
2. all other emails: newsletter, campaign, welcome, etc. The abandoned cart is in this category too. Here you can use your email app and collect emails.
Shopify sends out abandoned cart email, but you can turn it off (settings - checkout - go to the bottom of the page).
I hope it helps... Have a nice day!