Every time one of the cron-jobs that comes with pi-hole is carried out, an email is sent to root (even when successful). This is because the cron-jobs have an output - even when succesfull. It is - of course - suppressible 'by hand' by adding
at the end of the jobs in
/etc/cron.d/pihole. However, this file is overwritten every time the software is updated.
It would be nice (imho) if there was an option to suppress output of the cron-jobs (when successful) in the web-interface OR that default for the successful carrying out of such a job would be "null".