Donald Trump talks about giving drug dealers the death penalty. But if he goes down that road, it's going to get awkward.

FBI agents raiding the Pack and Ship. Schlubby postmen pulled out of their mail trucks. FedEx delivery guys lined up at the gallows.  

"The Postal Service is our biggest drug dealer," says drug expert Lex Pelger, host of the Greener Grass podcast about marijuana and organizer of Psymposia lectures about psychedelics. "It delivers more drugs than anyone else on the planet."

That's impossible to verify. But FedEx once faced a $1.6 billion fine for drug trafficking. Mailmen have been charged with accepting bribes to deliver cocaine and marijuana. And in an average year, the postal service seizes about 35,000 pounds of cannabis.

This matters, for two reasons:

1. Drugs can be awesome for recreational users.

"Charles," a 32-year-old Coloradan, said that the postal service plays a big role in his life.

When he grew more weed than he could smoke, he mailed it his dad to Wisconsin. When he wanted to try clean molly, he used the Dark Net, which mailed it to his home. When he learned about research chemicals — legal molecules that mimic illegal drugs — he had some shipped here from Canada.

Weed, molly and research chemicals can be useful medicines — though they also have risks.

"I like it better than going to a dealer," Charles said. "I feel safer. Like my (dealer) wears dreadlocks and Grateful Dead shirts. Dumb motherfucker looks like a dealer. But the mailman — who's gonna suspect him?"

2. Drugs can be turribul when recreational turns abusive.  

Younger Americans — those under 50 — die more often from drug overdoses than for any other thing. More than heart attacks, car wrecks, shootings, volcanoes, mudslides or alien invasions. And the numbers are still rising, up 30 percent last year.

A lot of drugs travel the traditional way — made from plants grown in Latin America, smuggled across the border in a truck or up some dude's booty.

But, more than ever, folks are ditching natural heroin and going synthetic. Chinese manufacturers of dirty drugs like stimulants, fentanyl and carfentanil love the Postal Service, since the sheer volume of packages means most won't be checked.

"Lots of meth goes through the postal service," said Bill Masters, a Sheriff in southwest Colorado and author of "Drug War Addiction: Notes from the Front Lines of America's #1 Policy Disaster." "I don't know how you're going to stop that."

Politicians propose fixes. Back in 2012, Customs and Border Protection tried a program called Air Cargo Advanced Screening to detect drugs coming in from overseas. But, six years later, fentanyl shipments from China are "basically guaranteed" to go through, according to a new congressional investigation. These led directly to overdose deaths.

And one of the world's biggest drug dealers — even if unwittingly — keeps operating. Drugs keep flowing, for better or worse. And stopping it seems as impossible as ever.