I have a Postfix Mail Server running on Unix FreeBSD 8.1-RELEASE on i386. The mail system is POP3 mail. It is running behind a Barracuda Firewall. I have 4 branches and the HQ. The HQ and the other bigger branches are connected through a VPN Link from an ISP. The other 3 branches are connected through Fixed Wireless Broadband and they are supplied by another ISP. All emails are configured on Outlook. The HQ and the other branch connected through VPN Link have no problems with sending/receiving emails internally/externally. The three branches that are using Fixed Wireless Broadband are able to send/receive emails internally and receive external emails. But they cannot send external emails. It stays at the outbox and returned with error "Relay Access Denied". Can someone help me on this issue? I am quite new to to Unix and Postfix Mail server and in deep problem.
Incidentally, this ended up in the wrong forum (this is for ISPConfig servers, which don't run on freebsd). You need to setup smtp authentication on both the server and clients.
Thanks. It was working previously when all were connected to one ISP. It just happened when we changed ISP.
it could possibly be as simple the branches not working now had fixed ip's, and your mailserver had those ip's set in mynetworks, with no authentication requirements. and when you changed isp's, their ip's changed, you may have changed them on your firewall, but not in postfix... this is assuming they're using a mailserver in their branch to relay to yours, or their mail clients connect to yours on port 25 with no authentication.
