Hi Marketing Team,
Thank you for your feature suggestion! I'll be sure to send this to our Product Team, but I wanted to share a solution as well as a couple of our support resources that may help you achieve this.
You can split test emails in Ontraport using our Automation builder. There is actually an filtering automation element called 'Split' that you can add to your automation path that allows you to test a/b versions of your emails. You can find more details about split testing emails in our support article here, as well as our OPU video that takes you on a deep dive into split testing. Hope this helps!