Going with what Joe said: Once sent it's definitive sent, it's now on a server and done with. So I can delete it.. Only reason to keep then is is you want to see if read.
You are correct! 👌
It may be definitively sent, but it's NOT definitively RECEIVED.
And I say that from experience, NOT as conjecture.
If you actually care about your recipient having received it, your reason to keep it is to see that "Received."
