Ok, I googled a bit. According to this[0] they're running PCR tests on samples from the air around the mail processing. I.e. outside the mail. In a sufficiently

Ok, I googled a bit. According to this[0] they're running PCR tests on samples from the air around the mail processing. I.e. outside the mail. In a sufficiently sealed package/enveloped that wouldn't be detected. Well, and with encryption the files going through mozilla are always properly sealed and they can only rely on external indicators such as reports or IP blacklists. So they're doing no worse than USPS. https://www.cidrap.umn.edu/news-perspective/2003/06/postal-service-test-anthrax-detection-systems-14-sites https://www.cidrap.umn.edu/news-perspective/2003/06/postal-s...