Block or redirect local mail delivery?

Is there a way to block/redirect local mail delivery?

We provide web hosting but not email services from our server. We provide email service through a different server and we automatically setup the MX Record to go to the other server.

On the web server we would like all local email references to an account to be blocked or redirected to the users email account on our other server.

For example, if our web hosting server is "server1.myhosting.com" and the web hosting account username is "anyuser" then an email sent to "anyuser@server1.myhosting.com" is being sent to the default "mail/new" folder for the users web hosting account.

Since we do not allow them email access on that server these messages can build up consuming their web space.

This tends to happen if they have CRON jobs generating errors and they didn't specify a different email address for CRON jobs. Or if they have web applications sending out emails that get bounced backed.

Deleting the "mail/new" folder doesn't work. It just creates a new one on the first email delivery. Removing all the permissions on "mail/new" kind of works but the messages build up in the mail delivery queue and I would prefer they be rejected immediately or redirected to the users actually email address.

Is there a way to do this?

And if possible, is there a way to do this automatically when new accounts are created?

Thanks!

Rich