I recently faced an environment where there is no MTA.

WTF? The reason is that people who work there get security audits on a regular basis, and the security people are usually mo...deratly skilled guys who blindly run a set of scripts, e.g. by ordering to disable Apache modules that "where seen enabled in /etc/apache2/mods-available/"...

To avoid spending days arguing with them and nitpicking with non-technical managers, the system is trimmed to the minimum - and there is no MTA. No MTA, so no cron output, so difficulty to understand why last night's cron job failed miserably.

Since it was not my role to reshape the whole business unit, I decided to hack a super-light, but functional way to get my cron output:

cat <<'EOF' > /usr/sbin/sendmail
#!/bin/bash
(
    echo "From me  $(LANG=C date)"
    cat
    echo
) >> /var/mail/all
EOF
chmod 755 /usr/sbin/sendmail

It works!

There is a companion logrotate script, to avoid filling the file system:

cat <<'EOF' > /etc/logrotate.d/mail-all
/var/mail/all {
  daily
  rotate 10
  compress
  delaycompress
  notifempty
  create 622 root mail
}
EOF

Bootstrap with:

touch /var/mail/all
logrotate -f /var/mail/all

You now can check your sys-mails with:

mutt -f /var/mail/all