This has to be done on a more global level, with the mail_job_status_format setting in the supervisor's qb.conf. The paths are evaluated and only used by the supervisor.
See section 10.2.44 in the Administation manual.
The mail templates have no conditional flow control in them, they're simply full of tokens that are search-and-replace targets.
If you want any finer-grained control, you'll need to dig into the callbacks, and at that point, you're past the functionality of the simpleCmd framework that most of the submission UI's in the QubeGUI->Submit menu use.