If you don't already have a Zapier account, head over to Zapier.com and sign up. Plans start at free (for 5 recipes and 100 Zap's a month). Zapier is a great way to connect two or more platforms based on actions.
Step 1: Connect Stripe (or your payment processor) to Zapier - If you have not already done so.
In the My Apps Area, Click "Add Connection", and search for Stripe (or your payment processor). You'll be prompted for your Stripe API Key (find it https://dashboard.stripe.com/account/apikeys), and click continue. **Be sure it is a "secret" and "live" variant. Note: restricted keys are allowed, but we will not be able to properly label/identify them.**
Step 2: Create Your Zap
Two options here, you can click the button to import your recipe or you can create you own version and customize it as you wish.
Option 1: Click and use my recipe
Option 2: Create your own version. Click Create Zap. Name your zap. In the trigger area, search for Stripe (or your payment processor). In Trigger Event, select New Event. Select your Account. Select New Failed Payment. Click Continue. Test your trigger.
In the Action area, search for Email by Zapier. In Action Event, select Send Outbound Email. (or choose another form of Action). Click continue. Set Up your action, customize this anyway you see fit. Here's what I have included in mine:
To: My email address
Subject: 🔴 Failed Payment in Kartra 🔴
You have a failed payment in Kartra. Here's more information:
I don't use any of the other fields but that is up to you to customize. Lots of options here.