Postfix - cannot connect to server to receive email

Question

Dear professional users,

I have installed Postfix email server on Linux, have created 3 users.

In windows, I have installed THE BAT program. Users may send emails to each other, but when I press Receive Mail - it brings the error: FETCH CANNOT CONNECT TO THE SERVER.

In Linux, I have trusted port 25 in firewall, I have allowed port 110 in iptables.

Note: I do not have sendmail server installed.

So, what is the reason that users may not receive emails?

Thanks in advance!

Answer 1

If some other process is listening on the same port it could block your service when it starts up. You can use netstat to determine if there is another process listening to the port:

http://www.cyberciti.biz/faq/what-process-has-open-linux-port/