Private messages - outbox

[4x4M38]

I am assuming that if I have a message in my Outbox the receiver
never got the message.

I have ten messages in my Outbox.

I wonder how many folks don't realize they have messages
unless they look up at that bar that says no new messages
or 1 or more new messages.

FYI - One can select to be notified by email if a new message is received.