Yes, but so what? I think I've made my point clear: you have no guarantee that there is a sender's copy for any email, now or at any time ever (RAM copies notwithstanding, obviously, and they are irretrievable in a very short time).
Some emails have only had a single copy saved to hard drive, that of the recipient.[1]
[1] In fact, there are usually two copies for the recipient, depending on the server and client. The email server will have a copy (maybe temporary and not backed up) and the client machine will also usually have a copy, depending on the server configuration and also on the client.