I have MercuryC configured to send to the relay by its IP name but the

managers of the relay are complaining that we only send to one machine.

I believe if you use the host name rather than the IP address  of the relay host it should get a different host each time.  That said, IIRC, it's up to the people running the multiple hosted system to rotate the connections to a specific host when there are multi-homed hosts.

In the distant past when we still used Mercury/NLM, we ran multiple

instances, but I can't find any way of doing that with MercuryC/32. 

Has anyone come across the same issue or a solution?

Not really necessary since MercuryC can make multiple connections to a specified relay host.  Personally I really like MercuryC.NLM (and still use it) so I can connect to multiple  SMTP hosts by running multiple instances of MercuryC.

We send outgoing mail via a relay that comprises 6 machines, all of which are listed in the results of a DNS lookup on its IP name.  I have MercuryC configured to send to the relay by its IP name but the managers of the relay are complaining that we only send to one machine.  The bottom line is they are applying rate limiting and say that if we used a different mail server, it would load balance between the 6 IP addresses.

In the distant past when we still used Mercury/NLM, we ran multiple instances, but I can't find any way of doing that with MercuryC/32.  Has anyone come across the same issue or a solution?

Regards

Alan