When email top level domain valid but subdomain invalid then check still passes

The DNS validation is passing for an email like the following: [email protected]

There is a misspelling of "environsment-agency" and if you check the DNS records for environsment-agency.gov.uk they show up as empty. But the library seems to only be checking the last part of the domain - gov.uk, not the subdomain as well.

This looks wrong to me. Is it possible to fix?