Email API v.2 - Reply To Object Explained

The property replyto is an object of emailAddress type.
It serves as the address to be used when a recipient replies to a message.
It is strongly suggested to use an email address belonging to the Sending Domain in order to avoid issues with antispam filters.

Request fields

replyto An Object indicating where to send the response if recipient hits "Reply To" button.

nameStringThe name of the reply to address
addressString (email address)The actual email address regarding the reply to information.
If the Object is present, this property must be a well-formed email address and not blank