nmh and OpenBSD

[stanl]

I'm running OpenBSD 6.5 on an old ThinkPad x220 using nmh to read email.
There is a short script in jerry Peek's book which when I log in should show me a list of unseen messages:

if mhpath unseen +inbox >/dev/null 2>&1
then
echo "Unseen mail in inbox:"
scan +inbox unseen
fi

Unfortunately, it doesn't work and not knowing any programming or shell scripting I have no idea why.

If anyone can point out what is wrong and how to correct it, I would appreciate it.

Thanks