Support

> The cronjob runs with -q but I can't find a way to silence the email every 15 min.

This is actually a Linux administration question, but you're lucky because I know the answer :) You just have to append

 1> /dev/null 2> dev/null

to your CRON job command line. This tells your operating system to redirect output messages and error messages to /dev/null (in other words, ignore them). Since the output of the CRON job is now empty, the CRON daemon does not send out an email on completion.

> When there is a message it the mailbox it works but I have set it to delete after retrieve and when there is no message I keep getting error messages. Might be related?

No, this is normal. Just ignore it.