How to allow a remote MX ?
If you have some user using remote MX , you should put the ip address of their remote mx server on ISP/Secondary MX Servers . Open the “ASSP web interface” go to “Relaying menu” , “ISP/Secondary MX Servers” , and click edit file , then add the remote ip and Save. NEW : with assp deluxe 2.8.0 and above, the cronjob ex_localdomains.php take care of this automatically .