Hello list, I have a encountered a very interesting problem and am curious if anybody here has a hint on that. I have a linux firewall / router with iptables. Let's call it defiant with ext ppp0/dynamic and int eht0 192.168.1.254 I have a linux mailserver Let's call it k-tanco with ip 192.168.1.200 I have iptables rules forwarding traffic on port 25 and 143 from defiant ppp0 to k-tanco. So far so good - everything works as supposed. When I telnet defiant from outside to port 25, I see the traffic (tcpdump) both on defiant ppp0 and k-tanco eth0. Now, I have a Nokia Series 60 phone with integrated email client. I set this email client to use the dyndns hostname of defiant via GPRS. I can check mails and send mails via my home server. That was the first strange point. A sending agent must be either use ASMTP, be on 192.168.1.0/24 or deliver mail for the local domains. So, the mailserver should have rejected the mail. While investigating, I found out the following: Incoming connections from the phone do NOT appear on defiant ppp0 (tcpdump). They appear on k-tanco eth0 with source ip 192.168.1.254 - the ip of defiant eth0. /var/log/mail claims, connect from defiant.net.local[192.168.10.254] and the header in the final mail says received from [169.254.0.7] (defiant.net.local[192.168.10.254]). Does anybody has an idea, what's going on here? Regards, Stefan