It'll be difficult to enforce though. The first reason is that the people tasked with enforcing it in the US (CBP ) also deal with controlled substances. They have much bigger fish to fry. He's using DHL, not USPS, which makes it even less likely that the glowies are opening his mail. He's bouncing the shipments around countries, so that they enter their destination country through many different points, further hampering investigation. As long as nobody is reselling them in the US, he'll be very difficult to track.
The tranny is operating out of Brazil, so various US authorities that could get him for crimes like practicing medicine without a license, operating a pharmacy without a license, selling unregulated drugs, etc, have basically no jurisdiction. Their Brazilian counterparts are too backlogged, nonexistent, and/or corrupt to give a shit. It does not take much to bribe a Brazilian official. He's probably a pharmacy tech who is making estradiol to Brazilian standards. There is way worse shit coming out of Brazil.
This will not change until someone gets an embolism/thrombosis and dies while taking this guy's hormones. Then there is a chance the FBI will care.
Tldr it's illegal but the authorities probably can't deal with it.