Hello. This is my first post here. I am having a problem with postfix that is really puzzling to me. I run a small website hosting company. On one of my servers I used to be able to send email via the forums, the control panel and in all other ways to any domain. Last week this server was hacked, we reformatted and reinstalled the OS since it was corrupted. We also installed an updated VHCS control panel (since we believe this is how the hacker gained access to the server). All installed fine and we thought it was all a success until we tried to send mail off the server.

We are using postfix as our email server, since our ISP blocks port 25 due to spam related issues we have had to edit etc/services to use port 2525 instead. We restarted postfix and now we can send/recieve email to/from any domain if we use a pop/smtp program. However for some reason we cannot send mail to the internet via any other means. This includes the forums, the control panel, website forms and so on. Why this is puzzeling is because I believe I set the services up exactly as before.

Our network,
We are using the forwarding option in postfix and have postfix forwarding mail to another server in our network that then in turn logs into our ISP email service and sends it out. The server that is being used to connect to our ISP hasn't been touched and nothing has been changed on this server so I know its the Debian box running postfix thats the problem. I am looking to resolve this issue quickly so that I can finally get our hosting company fully back online. Any help with this problem would be greatly appreciated.