[exim] Secondary mail server relay configuration

Hello,
I manage a mail server with 50 or so domains. I have set up another
machine to operate as a secondary MX for all these domains.
At the moment I am using lsearch;relay_domains so I just have a relay
domains file.

However it occurs to me that it would make the administration of new
domains easier if there was some way to configure the acl to accept a
message based on the MX host that it will be relayed to. Here I can
just list the primary mail server.

I was wondering if there are any security problems with doing this.
OK someone could set their MX record to our primary mail server and
then achieve relaying through the secondary, but it would be rejected
at the primary with MX points to local host so I dont see that they
achieve much.

Assuming there are no relay problems. Can I/How do I do it?

TIA


-------------------------------------------------------------------
Stuart Gall
Systems Administrator
-------------------------------------------------------------------
No user serviceable parts inside? Ill be the judge of that!