queuestats
Sadly there is no documentation for this plugin.
#!/bin/sh
#
# Plugin to count the qmail queue
#
# Magic markers - optional - used by installation scripts and
# munin-config:
#
#%# family=manual
#%# capabilities=autoconf
if [ "$1" = "autoconf" ]; then
echo "yes"
exit 0
fi
if [ "$1" = "config" ]; then
cat <<EOT
graph_title Qmail queue stats
graph_args --base 1000 -l 0
graph_vlabel mails in queue
graph_category mail
queue.label queue
queue.type GAUGE
queue.min 0
EOT
exit 0
fi
echo -n "queue.value " && /usr/bin/find $queue/mess/ -type f -print | /usr/bin/wc -l