block from sending email to external domains

[tcdrake]

I am trying to setup a filter rule to deny users from emailing outside of the company domain. I believe I have the filter set correctly. When I test within cPanel it shows it is working but when I try it via webmail the emails are delivered. Below is the simple filter I have in place.

aaa.com is the company domain
zzz.com is all external domains

Rule
Any recipient does not contain aaa.com
Fail with message "Denied"

Test results from within cPanel filter section.

e Filter has matched the following condition(s):
foranyaddress $h_to:,$h_cc:,$h_bcc: ($thisaddress does not contain aaa.com)
$thisaddress does not contain aaa.com

Extracted address test@zzz.com
Return-path copied from sender
Sender = myaccount@aaa.com
Recipient = myaccount@aaa.com
Testing Exim filter file "/etc/vfilters/aaa.com"

Fail text "Denied"
Filtering ended by "fail".


Like I said, the above test works but if I try sending an email via webmail they are delivered without being denied. Any ideas on what I am missing here?

[tcdrake]

I'm being told by my hosting provider that the cPanel filtering doesn't work on outgoing emails only incoming. Can someone confirm this for me? If this is true does anyone have any suggestion on what I can do besides setup an email server onsite?

Thanks!