In order for the SpamTitan Cloud servers to accept mail for your domain, you first have to add the domain to your account. 

To do this log in as a Domain Group Administrator.  Go to Settings > Relay Settings and click Add.  You will be presented with the following window:


Domain:  Your email domain
Destination server: The mail server to which you want you clean, filtered mail delivered.  This will usually be the external IP address or domain name of your site, or your Office365 domain name.
Destination Port:  25 is the default SMTP port.  All mail servers will use port 25 unless configured otherwise.
Enable MX Lookup:  This option allows you to use the MX records of a different domain to identify the destination server.  This option will not be used by most SpamTitan Cloud customers.
Recipient Verification:  This feature allows the SpamTitan Cloud servers to verify if a recipient address exists.  There a re a number of methods, the one we recommend using is Dynamic Recipient Verification.  In order for Dynamic Recipient Verification to work your mail server has to be configured to reject invalid addresses.  We have guides on how to do this for various mail servers here:

Exchange 2007, 2010 and others:
Recipient Verification

Exchange 2013 & 2016:
Dynamic Recipient Verification using Exchange 2013 and 2016

RBL Checks:  This settings allows you to enable or disable RBL checks for this domain.  This test checks the IP address of all mail servers sending mail to your domain against lists of know spammer IP addresses.  This test is extremely effective at blocking spam, we strongly recommend leaving this option enabled.

Once your domain has been added you can test to see if mail can be delivered to the destination server:


Click the test button shown in the image above, enter a valid email address and click send.  The mail should be delivered to the specified address.