The App generates a RMA number as soon as the Request is “Approved”.  So in order to automatically send the RMA number by email , simply include it in the Approval Notification Email.  The customer will get the Approval Email with RMA number and all other information.

You can also use the Approval Email to send the additional instructions to the customer. Pls take note this will also work if the Request are set to Auto-Approve.

RMS - Set Request Approval Email