[Skunkworks] Problem using exchange 2007 as a relayhost.

Hi Guys, Our linux(postfix) server has been sending emails using exchange 2003 as the relay, but since we upgraded to exchange 2007 it cannot send external emails anymore, the linux server has already been added as a relay in exchange, has anybody ever faced this challenge. -- Regards Felix Mwai Software Developer. Mobile 0720453684.