During daily purge of statistics, the cron has output and hence send emails like:
Gathering stats to purge...
* Opening database table 'plugin_statistics_diskusage_group'
-- Parsing stats between three months and two years old
* Opening database table 'plugin_statistics_diskusage_site'
-- Parsing stats between three months and two years old
* Opening database table 'plugin_statistics_diskusage_user'
-- Parsing stats between three months and two years old
Purging all data marked for removal
This should be dealt by a logger (and no emails should be sent)