I am in process in of migrating to a new DSL service. As of right now, I have a firewall/proxy configured and listening on one of my new IPs from the vendor that I am migrating to..

My question is, how can I test that e-mail is being handled correctly by the new Firewall/Proxy? I have not done the DNS change yet, because I want to verify that the new Firewall/Proxy is configured and functioning properly before I make the DNS change.

Is there a way to send an e-mail to user@x.x.x.x instead of user@domainname.com?

Any help or suggestions would be greatly appreciated.

Yes, you can send mail to user@x.y.x.q .No special actions needed.

if you use postfix on the server add the ip address as a destination in /etc/postfix/main.cf

mydestination = mail.mydomain.net, 123.45.67.89, $myhostname

if it's not listed there it will try to relay it to the recepient which is itself, and will generate an error indicating so. it will also send an email to the sender of the letter with the error.

one pretty cool thing you can do with the domain name if they have email relay is that if your name mydomain.com will be relayed to your name service mailserver by your server if you don't have it listed in mydestinations.

you can have them forward the mail to another pop server where you can get it with fetchmail.

you can put something like mail.mydomain.com in mydestinations and it will deliver that mail locally. If your server is down the name services mail server will pick it up and forward it.

If your isp is really dependable and your power never goes off, I guess it would not be necessary.