If you tried to setup your Smoothwall Filter and Firewall to send email alerts through your internal mail server, and you find that your mail server is rejecting the attempts to send mails, you might need to configure a full host and domain name.
Often mail servers will ask for a full host and domain name from the sending server.
It rarely matters what the actual value is but Smoothwall host names do have to include host and domain name. Often we see Smoothwalls only configured with a host name and no domain. This can cause the receiving to reject the mails.
You can configure a full host and domain name in the Smoothwall Filter and Firewall on the System Preferences Hostname page, see our help topic, Changing the system's host name and how it identifies itself to the network.