Need to make Scalix mail server work with Cell Phones

We need to make our mail server work with our cell phones. We are running Scalix 11.4 on a server running Centos Linux 5.2 Emails can be received fine on clients not on internal network (either cell app or Outlook) but can NOT be sent. I think the settings will not let mail from a machine not on internal network be sent through it. All machines on internal network can send and receive mail fine. Mail is only rejected (not sent) when it comes from outside internal network. So, to clarify...settings on Scalix need to be changed to allow mail to be sent (via cell phone or pc) from outside internal network.