What you can do is to set up a dyn-dns for this dhcp interface and iclude that in the set of the MX records... At any IP change you could encounter smtp unreachability but it's not a big deal as the backup MX's would collect the emails and send it to you at a later time...
Note that netfilter has nothing to do with your question and this solution. Ramin On Fri, Jun 14, 2002 at 01:19:24PM +1000, Ian Pollock wrote: > Hi, > Can anyone tell me if this is possible, we upgraded our internet access from isdn >(small isp) to broadband (telstra). We had a static ip of eg:210.20.20.20 from our >small isp on the isdn, with the new cable connection we get dhcp ip address which >makes it hard for mail routing. Ok the big question can I alias the old static ip >(small isp) we own of 210.20.20.20 to my external etho dhcp (from telstra) device (ip >of 211.50.50.50) on my cable connection and route my mail through this way. I have >included a few rules that I have in mind. Can anyone tell me if I am going down the >wrong path with this and if they have any other way of doing it could they let me no >(maybe I have to use pop3). Any help with this would be greatly appreciated, I tried >to explain as best I could. Ian > > iptables -t nat -A POSTROUTING -o eth0 -s my_mail_server -p tcp --dport 25 -j SNAT >--to OLD_ISP_mail_server_ip:25 ## can this work?? > > iptables -t nat -A PREROUTING -I eth0 -p tcp --dport 25 -j DNAT --to >my_mail_server:25 ## I no this works... > > ps... any help with "how to alias" would be great too
