When Appending a Canned Response and ticking the Append checkbox neither the canned response nor any attachments in the canned response are sent by email.
I have checked using PHP mail and SMTP settings.
I managed to fix this for my server at least
See -> http://osticket.com/forums/showthread.php?p=34407#post34407(http://osticket.com/forums/showthread.php?p=34407#post34407)