ClearOS can be configured to be an antivirus and antispam mail gateway. For example, you can put a ClearOS system between the Internet and a Microsoft Exchange server.
You need the following software packages installed on the system:
Configuring the mail gateway is not much different than configuring a regular mail server. Go to the Antivirus and Antispam sections of the user guide to configure these software modules. The configuration options for these modules are straightforward.
For the SMTP Mail Server, the important option for configuring a mail gateway is the Mail Forward Domain List. If you are running your mail server at 192.168.1.10 for the domain example.com and example.org, the Mail Forward Domain List would be:
That is all there is to it. At this stage, you can double check that everything is in order. Change the outgoing (or SMTP) mail server settings in your mail client – use the IP address of the ClearOS gateway. Send a test message to your target domains (example.com or example.org) to make sure they arrive. You can also send a test spam message and Eicar test virus if you wish.
The SMTP mail server port (25) must be open on the firewall. If you were running your ClearOS system as an Internet gateway, then you might have a port forward rule defined for your existing mail system. You want to disable this port forward rule!