Hi all. I?ve inherited an Exchange server that will not relay to external addresses. We have users who are normally on the go and they collect their email via POP3 from our server. When they send messages, they normally get back an error message such as: The following recipient(s) could not be reached: 'user@xxxxxxxxxx' on 4/02/2006 9:34 AM 550 5.7.1 Unable to relay for user@xxxxxxxxxx All the literature I?ve looked at on the Microsoft website all points to a Cisco router as being the culprit. However, we are using a Red Hat Linux 9 based router! There is no other literature on Google that is shedding any light on my current situation. I have already double checked the relay settings and all appears to be in order. However, I could have missed something in my desperate attempts to find a quick solution. As such, please let me know what I need to add to this message to get a resolution soon. Cheers, Anthony.