Hey There,
Quick and dirty if you want to get email no matter what distro you're on. If you're cron entry is, let's say:
59 23 * * * /usr/sbin/reboot
just change it to this:
59 23 * * * /usr/sbin/reboot 2>&1|/usr/lib/sendmail
you@yourdomain.com
Now as for the reboot notification, in and of itself, you may still have issues since the machine is shutting down. If you could use a program like shutdown with the -g flag to set a grace period, like 60 seconds, the reboot would have time to send out a mail before it potentially cripples the mailing subsystem by sending it a TERM signal at reboot
Best wishes,
Mike