[otrs] Configuration Problem (Mail)

Hi everyone, I wonder if anyone can help me. My main problem is that the machine is on an internal network - and does not have a DNS or MX record associated with it. I am using an smtp address to get jobs into my queues, but as soon as the machine tries to send an email (in reply to a ticket or a status update) the remote mail server bounces the email because there is no MX record pointing back to my machine. Is there any way around this? My initial thought would be to relay mail through my main mailserver on the local network.. Is this possible? Thanks