I have ISPConfig 3 set up and running well. However I'd like to use my server to accept email for an external domain, and then forward it to the destination mail server (the destination mail server doesn't have very good spam filtering). I believe I need to add the domain and IP address to transport_maps and add the domain to relay_domains, however I don't really know how to do this when working with ISPConfig (read: I don't want to screw up the working config).
Login to ISPConfig, then add the domain to email routing and then either the email recipients or @domain.tld for the whole domain under Relay Recipients. Finally, add a record under Spamfilter > user / domain for the domain to set the spamfilter policy that shall be applied to emails for that domain.
