Use remote mail server to send mail from PHP scripts

By default WHM restricts outbound requests on port 25 and 587 to root and exim. When other users try and make a connection to a remote IP on these ports, that connection is routed back to localhost. This is to prevent unprivileged users pumping spam out of the server. Is there any way I can keep this protection, but allow access to a remote server? The remote server requires authentication and is on a fixed IP.