Give users more control over Exit Intent Popups on the dashboard. Let them turn on/off, adjust designs and A/B test.

Whenever a product is out of stock, having an email form field in place of the "add to cart" button that customers can enter their email address in to receive emails when the product is back in stock. There are other apps that do this, obviously, but I personally love cartstack with all of my heart, so I would prefer if they did it. I think one of cartstack's greatest strengths is the reporting dashboard, and I love having all of the analytics in one spot.

I would love to be able to annotate the timeline with significant changes that we've made to our campaigns. Instead of only keeping track outside of Cartstack. There are specific dates when we've enabled campaigns and would like to be able to see those in the dashboard.

Include a spam plugin on the email builder that lets you check spam score and ways to improve it.

Have the ability for customers to add additional customizable campaigns outside of cart and browse abandonment. It would allow us to customize campaigns for customers leaving specific pages outside of cart/product abandonment. This will also help multi-language sites help keep all campaigns under one roof without needing so much customization.

Allow the ability to A/B Split Test Browse Abandonment templates similar to Cart Abandonment.

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.

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.

Create simple on-page abandonment surveys to gather qualitative data from users. For example, as someone is exiting the site, display a one question survey - "What is stopping you from buying product X today?"

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