Hello @EvaLee,

Thanks for sharing your question with the Klaviyo Community!

Although Klaviyo is able to identify when a customer has opened or clicked an email, Klaviyo is unable to track when a customer replies to your emails. Email replies are directly handled by your recipient’s inbox provider sending a message to your designated reply-to address and doesn’t go through Klaviyo. 

When emails are sent from Klaviyo, we automatically apply a tracking pixel at the bottom of your emails which triggers an Open Email event when the email is loaded. Similarly, Klaviyo is able to track a Clicked Email event when Klaviyo’s click tracking, which is automatically applied to all links in your email is loaded. You can learn more about how Klaviyo is able to track when someone opens or clicks an email from the Open and Click Tracking subsection of the Conversion Tracking article. 

Because of this lack of identification of recipients who respond to your emails, there wouldn’t be a means to track these customers who have responded to your emails within Klaviyo to either capture and send a campaign or trigger a flow to automatically serve to them. If you did notice a recipient replying to your emails within your reply-to address’s inbox though, you can manually send these customers a one time email with a coupon code generated within Klaviyo by either using a Campaign send or emailing this individual directly from Klaviyo as detailed in the How to Email a Single Person Using Klaviyo article.

To send an email to this customer via a Campaign, you would need to capture this individual either through segmentation with rules such as “Properties about someone, Email equals X” and using this segment as your recipient group. Or alternatively manually creating a list and adding this recipient to the newly created list via the quick add function to be used as the recipient group of the campaign send. 

I would also recommend taking a look at the How to Use Coupon Codes in Klaviyo and Unique Coupon Codes for Shopify articles to further learn on how to generate and provide your recipients with a unique coupon code from Klaviyo. 

I hope this helps!

David