Nicola Twilley in The New York Times:
Scientists agree that the main means by which the SARS-CoV-2 virus jumps from an infected person to its next host is by hitching a ride in the tiny droplets that are sprayed into the air with each cough or sneeze. But with deliveries now at holiday levels as locked-down Americans shop online rather than in person, the question remains: Can you catch the coronavirus from the parcels and packages your overburdened mail carrier keeps leaving at your door? The first formal process for curbing the spread of infection by detaining travelers from an affected region until their health was proved was instituted in what is now Dubrovnik, Croatia, in 1377, against the bubonic plague. (This temporal buffer was originally 30 days, but when that proved too short, it was extended to 40 days, or quaranta giorni, from which we derive the word “quarantine.”)
Mail disinfection soon followed, as the then Republic of Venice extended and formalized the quarantine process to include cargo. Items that were considered particularly susceptible, including textiles and letters, were also subject to fumigation: dipped in or sprinkled with vinegar, then often exposed to smoke from aromatic substances, from rosemary to, in later years, chlorine. Once the items were treated, a distinctive wax seal or cancellation was usually applied to them, so the recipient would know where and when the disinfection had been carried out. (Such marks often provide the only remaining evidence of the ebb and flow of disease; some minor outbreaks of plague or typhus in remote areas of medieval Europe, for example, would have been lost to history without their postal traces.) The diseases changed, but for centuries mail disinfection techniques remained largely the same. As recently as 1900, during a plague outbreak in Honolulu, letters were routinely disinfected by clipping off the two opposite corners of each envelope and then spreading a batch of mail out in an airtight room filled with sulfur fumes for three hours.