What do I do when postfix reports, "Cannot assign requested address"?

You should remove the IP address before the port in your /etc/postfix/master.cf. For example, if the line now reads:

12.167.295.8:10026 inet  n       -       n       -       10      smtpd

Change the line to look like this:

:10026 inet  n       -       n       -       10      smtpd

If you are running multiple instances of postfix, then you should also consider adding the following line to the main.cf for the postfix configuration that is reporting the error:

smtp_bind_address = 0.0.0.0