Can you smuggle a person in diplomatic mail?

Writing about the ongoing Julian Assange standoff at the Ecuadorean embassy in London yesterday, I wondered if it would be possible to smuggle the Wikileaks founder out of the country via diplomatic mail, if the British government refuses to grant him permission to leave. Dan Trombly alerted me on Twitter that there is precedent  for embassies doing this sort of thing, particularly Egypt. This led me to the strange case of  Israeli-Moroccan double agent Joseph Dahan.

On Nov. 19, 1964, the New York Times reported on Dahan’s discovery at the Rome airport:

Italy expelled today two Egyptian diplomats accused of an attempt to "air express" to Cairo a trunk marked "diplomatic mail" but containing a man who had been drugged bound and gagged. The two officials are Abdel Moneim el-Naklawy and Selim Osman el-Sayed, both first secretaries of the United Arab Republic’s Embassy here. The man in the trunk has been identified as Joseph Dahan, 30 years old, a Moroccan. [The man was identified Wednesday by an army officer in Israel as Mordecai Luk, an Israeli renegade] The man told Italian policemen that he was kidnapped in a café in Rome and taken to an apartment and that the following day he was drugged and put into the trunk. He was freed after an airport guard heard him moaning as he was being put aboard an Egyptian airliner. […]

There was speculation that the trunk, especially fitted with a small seat and adjustable foot and head supports, had been used for other such "shipments," because the exterior appeared worn.

The trunk was addressed to the United Arab Republic’s Ministry of Foreign Affairs in Cairo. One tag identified the trunk as "Diplomatic Mail No. 33."

In a fairly overwrought editorial on the case, the Times wrote: 

When life enlarges upon the wild fancies of the spy thrillers, we are astonished. In the case of the macabre story of Joseph Dahan (or whatever he name may be), whom the Egyptian Embassy encased in a fiendishly constructed trunk and labeled "diplomatic mail" en route from Rome to Cairo, we can also be horrified.

The bland disclaimer of the Egyptian Ambassador could be given some credence but for a sinister fact announced by the Rome police: The trunk "shows almost definitely that it had been used this way before." Is it, perhaps, an old Egyptian custom? Certainly it is one of the oldest of Egyptian stories, which Plutarch made forever famous: About the god Osiris, whose wicket brother Set lured him into a coffin, nailed him up and cast the box into the sea. Osiris, it will be recalled, but then he was a god. Dahan was no god; he was just lucky.

So it seems it is possible, but helps if the person being shipped is willing.