Reading your online help under the topic Sending Files (A Walkthrough) it seems as though you send the e-mail to the recipient before the file is sent to the server.
I started to send a file, then realized that the wrong file was being sent, so I cancelled the send. I presume that the recipient received a message that there is a file for him to download, when in fact there isn't a file.
Wouldn't it be better to wait for a successful file transfer before sending the e-mail to the recipient?
There are number of reasons why the notification email is sent when the file is originally published, some of them technical in nature. However, one of the simplest to understand is that when a recipient is notified early in the transfer process (rather than at the end), they have the ability to monitor the file's transfer progress. If the file happens to be exceptionally large, then they have the ability to make an informed decision as to how they want to download the file in question.
For additional information, please review the "How It Works" section of the online help. The online help can be found at: http://magicvortex.com/Help/