Dear Aaldrik,
Even when I change my smtp server settings to something silly, before the cron checks for backups, there is at least the two lines "Starting activity modules" and "Finished activity modules" usually with things like the following in between.
Server Time: Tue, 1 Feb 2005 14:29:27 +0900
Starting activity modules
Processing module function assignment_cron ...done.
Processing module function forum_cron ...done.
Processing module function journal_cron ...done.
Processing module function workshop_cron ...done.
Finished activity modules
Running backups if required...
etc.
I wonder why the stuff in red is not there in your cron.php
Tim