Comment # 2 on bug 919687 from Per Jessen

(In reply to Sebastian Freundt from comment #0)
> How to reproduce:
> 
> 1. Put in crontab:
> 
> * * * * * false
> 
> 2. Wait
> 
> No mail is ever sent.  It is very unclear from crontab(5) under which
> circumstances a mail is sent.

Cron will, to my knowledge, send an email when output is produced.  The return
code from whatever was executed is irrelevant.

Try adding this to your crontab:

* * * * * echo blurp