Not to mention that in any Internet mail system, the Sent Items folder has no real link to what's been sent; the fact that your outgoing emails also get appende

Not to mention that in any Internet mail system, the Sent Items folder has no real link to what's been sent; the fact that your outgoing emails also get appended to your Sent Items folder is a pure client convenience, done via a different protocol over a different connection with a different copy of the message body, and it's quite possible for them to show up even if the transmission itself failed.