Check if the server is running properly with the following command:
telnet localhost pop3
You should see something like this:
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
+OK Dovecot ready.
Modify the aliases
nano /etc/aliases
Make sure the following lines are present:
postmaster: root
root: [email protected]
Reload the aliases and restart Postfix:
newaliases
service postfix restart