UpPromote uses Amazon email service to send emails to your affiliates. Using Amazon service, emails sent to your affiliates will have the sender's email address as [email protected] by default. In this default option, when an affiliate replies to an email, merchant cannot receive it.
If you want to set up so that your email is used as sender's email, go to Settings section and enable Use your email as sender's email:
By activating that feature, not only the merchant email address would be displayed as sender's email when sending to affiliate, but also when an affiliate replies to an email, merchant would receive that reply.