You cannot send emails to specific domains in Trend Micro Email Security (TMEMS). The mail tracking logs display the following message:
Recipient domain not found.
The error happens because the domain name of the recipient may be invalid or could not be resolved by TMEMS DNS servers.
Make sure the recipient's domain has a valid A and MX record. To check if the recipient's domain has a valid A and MX record, you may run NSLOOKUP or use a third-party tool such as MX Toolbox.