The output is actually coming from fetchmail not startmail. Startmail is run by cron and simply fires off fetchmail. Any output generated by a cron task is emailed to the root (admin on e-smith) account.
To prevent the messages, redirect the output of the fetchmail calls in startmail to null. For example, put this into the startmail template (at the appropriate locations, of course):
$OUT .= " /etc/fetchmail >/dev/null 2>&1\n";
The outputs from grep and killall should be likewise redirected.
Disadvantage -- if there are ever errors in any of these calls, you won't see any cron mail about it.