This article explains how to enable the automatic domain-creation feature in SecurityGateway. This feature is configured to have email sent through the server with an unknown domain will be added to the database, with default information.
SecurityGateway by default creates new accounts when an email address comes in for a currently unknown user, after using the user-verification source associated with that domain to verify it is a valid user. If you have multiple domains, however, you can enable this option so you do not have to input each domain individually into SecurityGateway's database.
From the Dashboard, after logging in:
Locate the Accounts section
Click on Automatic Domain Creation
Check the box next to 'Enable automatic domain creation'
Click Save
SecurityGateway will then create new domains based on emails coming in, using any default verification sources to verify the users are valid, and any default mail servers to send the message onto.
IMPORTANT NOTE: Use this option only after verifying your email server is not set up to allow open relaying of messages, because this option will allow for the automatic creation of domains you do not actually host, and users on that domain, when mail is sent through your network with a nonlocal address, and therefore can cause the amount of users in the database to rapidly increase. If you are not sure your server is set up to not be an open-relay, contact your email-server solution provider or consult the documentation for that mail server.