The previous default for new accounts is to not set the MAILTO= value at all in the crontab. This defaults to sending email to that User if the cron generates any output. The issue with this is Users often never check their system email accounts,typically flooding it with more messages than the directory can efficiently manage, as well as causing issues with the backup, since DA/tar cannot easily read the contents of the oversized Maildir. The solution is to default new accounts to use: MAILTO="" in both the crontab.conf and the actual crontab (for direct_crons=1, which is the current default). Existing accounts will not be affected. If you'd like, you can change the cron email to a blank value in a given User's cron page, and save, to prevent any further emails.