If you run qpsmtpd-apache on a box with SELinux enabled, you'll need to
allow apache to listen to your SMTP port, typically port 25.

The following command allows apache to listen on port 25:

    semanage port -m -t http_port_t -p tcp 25

Use the -d option to remove this permission:

    semanage port -d -t http_port_t -p tcp 25
