Typology rule filtering for transactional emails

Hello,

We would like to implement a typology rule so that transactional emails can only be sent to certain domains.

We have added a "filtering" typology rule to the Transactional Message typology in several different targeting dimensions (rtEvent, address, recipient) but it does not appear to be working. Does this need to be done on the RT instance? We are looking for guidance on how to achieve this filter.

Thanks,
Skyler