Normally in a domain, there is a record that tells where the mail for that domain should be delivered (MX record). This should point to your domain's email server.

Image 1 shows a typical domain, with one email server referenced by the MX record. All messages sent to this domain will be redirected to the intended mail server.

In this situation, all filtering must be done in the email server, or in the end-user's email applications.

To use the ETMX filtering system, you need to register for a account first and add you domain.

You will need to change your domain's MX record, this operation must be done with the entity you used for registering your domain.

Then you must do a simple MX Record change, after this alteration, all incoming domain messages will be directed to the ETMX filtering system (Image 2). The system will apply the filters in your chosen plan and will only deliver to your original mail server the messages that pass the filters, the spam/virus will be dealt according to your plan's policies (usually they're quarantined).

Quarantined messages can be released/deleted later, by users with permission.