Can't enable Restrict outgoing SMTP to root, exim, and mailman

[Archmactrix]

When enabling "Restrict outgoing SMTP to root, exim, and mailman (FKA SMTP Tweak)", I got a message that said that was an error updating it.

Enabling SMTP tweak before has not worked either.

I'm on a VPS server.

 

[thewebhosting]

This option may not work for some VPS platform. Check the following comments under WHM -> CSF configuration:

# This option uses the iptables ipt_owner/xt_owner module and must be loaded
# for it to work. It may not be available on some VPS platforms

 

[Archmactrix]

Thank you.

I hope that my host is willing to look into this then.