Growing number of e-mails sent, but not being received.

I think they ARE being received. People are now aware that they are being held accountable for knowing (or doing) whatever was in the email. As a result, when they are "caught" not knowing something, or not doing something, they are claiming "I never received that email!". How could most people prove otherwise? I liked it when we could receive "your email has been read" receipts.