Replies to customers from within the CMS can make use of pre-set response blocks that can be appended to the email body.
These are created and managed in the messaging area when replying the the enquiry.
The link to create a canned response is found in the bottom right of the message area.
The same link can be used to edit or delete your responses.
Any responses added are found at the bottom left of the message area, enabled by a check box.