Date: Wednesday, July 19, 2017 23:31:10 +0000 From: Chad Cordero ccordero@csusb.edu
It’s being rejected before it even reaches the mailbox, so forwarding won’t work. Crond should really be using the MAILTO variable and it’s not.
In my testing, this worked as advertised. Changing the "MAILTO=" in /etc/crontab from the default "root" to either a local username or a remote address resulted in the crontab messages being delivered to the desired mailboxes. I think I'd put a test command into the crontab and watch the logs to see what might be going on -- including making certain that the crontab is reloading correctly after changing the "mailto" value.
Separately, but related, did you run newaliases or postalias after you added the entry to "root:" in /etc/aliases?