Irradiate all mail. Sterilize the $hit out of it. We have the technology.
You heard it first, right here on FreeRepublic.
Sunshine destroys anthrax spores, but very little else does. Heat doesn't, radiation doesn't. It's resistant to explosives. That's precisely the reason why anthrax was developed as a weapon, because it's tough, whereas most bacteria and viruses are fragile.
One of the unintended benefits of the current crisis, is that in the past congressional staff and their elected officials always seemed to want to ignore email and only really count, hand written hardcopy. I think a lot of staff will want to encourage the sending of "virus/bacteria" free electronic mail as opposed to the type that can make one sick.
Back on thread, I hope that very high Gamma or beta radiation serilization equipment is installed in major postal facilities and at major government buildings as it would bring this to a conclusion pretty quickly.