Using SMS messages to retarget users who have entered their phone number and have not finished their order. This would send the user a link to go back to your site and also give them the ability to reply with a question about the product(s) in their cart.

Add web push notification campaigns for abandoning website visitors

If a user abandons the site and later returns (either by themself or through a recovery campaign), automatically re-populate the form fields that they entered data into during their last visit. This will save time for user (and reduce friction leading to abandonment).

Being able to put Cartstack emails into test mode is great, but if you need to put it into test mode after finding an issue, that does not stop the queued emails from sending. It would be great to be able to pause all emails from going out while diagnosing an issue. It would also be great if you could clear the entire send queue if you know that those emails are going to send to people who shouldn't get them.

Ability to send a targeted email blast to visitors that abandoned a specific product during specific time period. For example, if you changed the price of a product you might want to email everyone that has recently abandoned that product about the price reduction.

Show a small popup when a customer completes an action on a site like a purchase. Give proof to customers that others are buying etc

Ability to add conditions (basic markup) in email templates to display different content based on different scenarios. For example, display coupon code if the user's abandoned cart is greater than $100; or if the user has a specific product SKU in their cart then display a free shipping message, etc.

I've heard the Messenger channel to be 4-10x more effective than email. I'd love to see a Messenger integration and automation feature!

Create a new checkout form analytics report that shows each field as a step in the checkout process and where users are most likely to abandon.

Ability to send entire email sequence whether it be two or three emails. Currently, if abandoned customer clicks on 1st email they will never receive 2nd email which most often times contains an offer/discount. This results in lost sales or adding offer to 1st email, neither of which are good options.