I guess the point I was trying to make is that sending an email, or showing that you've sent an email also doesn't prove that they have received or read it. I t

I guess the point I was trying to make is that sending an email, or showing that you've sent an email also doesn't prove that they have received or read it. I think in edge cases, it's probably possible to forge that you've sent an email in the past when in reality, you've sent that email this morning. By using something like the aforementioned service, at least you can prove without a doubt that the message was sent at a specific time, putting the impetus on the receiving party.