Customize email message sent to each signer on a per-envelope basis

Hi everyone,
 

Via our DocuSign integration/ API, using recipients[].signers[].emailNotification.emailBody, we would like to customize the email message sent to each signer on a per-envelope basis as follows:
 

- Embed protected images in that email message using CID (Content-ID).
 

Is this approach supported by the DocuSign API? If not, we would greatly appreciate any suggestions or recommended approaches to achieve this functionality.

Thanks!