The Additional Details page contains fields like Custom Email Subject, Custom Email Body, Email Notifications / Reminders, and Expiration Periods. You can specify the default subject and body for an email that is sent to the DocuSign recipient when a document is sent for eSignature. Salesforce merge fields are supported in the email subject and body. The default text is already added in the Subject and Body fields. Entering a blank email body provides the DocuSign default email message. We recommend that you do not use a blank subject.