A reply to a transmittal can be generated from within the Incoming Transmittals register using an item of Mail creating a link.
To configure a Transmittal Workflow:
In the Transmittal Inbox or Sent Items go to More, Configure Transmittal Workflow.
Double click the Transmittal type to open.
Use the + button to select the relevant mail types. Select a specific mail type, ANY for any mail type or N/A if replying to transmittals using Mail is to be prevented.
Click Save.
Repeat for all Transmittal Types.
Mandatory Recipients can also be added or removed in the Configure Transmittal Workflow window.