Well, I checked my php.ini and short_open_tag is on, otherwise dolphin would not work, and instead show a lot of script lines between <? and ?> in the browser:-
php.ini
; This directive determines whether or not PHP will recognize code between
; <? and ?> tags as PHP source which should be processed as such
short_open_tag = On
Which tell me that the dolphin script can't tell if it's on or off, and thus removal of the cron job stops the constant emails being sent.