OS X Mavericks :: 10.9.4 / Sent Mail Disappeared?

On My MacBook Pro, using my Apple Mail, iCloud account, in the mail app, I was working on a very long detailed email and saving it as a draft in between, I finally finish the email and check it for errors and then send. The little blue line in "mail activity" shows the message being sent. Then I go to my sent folder and the message is nowhere to be found? I follow in the instructions for rebuilding etc and same thing, nowhere to be found?

How I can possible get this email back? this happens so much on Apple Mail which is so so frustrating especially when you make the attempt to constantly save the email and it still disappears. So now I don't know if the email sent, and it's not a situation where I can merely contact the sender to see if they got it. Another issue with the iOS on iPhone is that the new one makes the swish sound to appear as if the any emails sent miraculously send in a split second, when they don't sometimes they don't send at all. But this swish sound gives the impression that the email was indeed sent, I find this misleading. Because on the previous iOS it only made that sound when the email actually sent.

Info:
MacBookPro, OS X Mavericks (10.9.4)