You can update the body of the message.
The body can be updated only by the sender or by other users who are allowed to change them by the sender.
But you cannot change the setting of acknowledgment status.

1. Click the app icon in the header.

2. Click Messages.

3. On the "Messages" screen, select a folder and click the subject of the message you want to change.

4. On the "Message details" screen, click Edit.

5. On the screen to edit messages, change the subject, body, and attachment fields as necessary.

   For details on the items, refer to Sending Messages.

6. Confirm your settings and click Save.