Another way is to not delete the message after signoff, then add your comments above the item and send it as a message to the staff.
Be cautious about doing this if you have more than one item to sign off. If you edit the sign off notification in the Messages list to send it to a staff member, and then delete the copy from the list of messages, when you return to the sign off window, clicking will sign off the next document in the sign off list without viewing it.
