Ask Slashdot: Could E-Mail ever Replace Snail Mail?

dlc asks: "The recent USPS question got me thinking. One of the major things traditional mail has going for it that email doesn't is the fact that, for the most part, signing a letter (marking it as authentic) is easier to do, or, at least, the technology to do so is much more common, and is much more widely understood. Similarly, one of the obstacles standing in the way of universal acceptance of email as a legitimate means of reliable transmission is the fact that it is difficult to verify the sender of a message. Digital certificates and a world wide (or at least wide-spread) public key infrastructure would go a long way towards removing this obstacle. My question for the slashdot population is this: Under what circumstances do you see digital cirtificates, PKI, and encryption in general becoming part of normal email usage, to the point where people have as much confidence in the authenticity of email as they do in regular mail? "