When you choose to send a file as-is, what happens when your recipient clicks on the link is largely determined by how her web browser or e-mail client is set up.

For example, you sent your friend a Quicktime file named vacation.mov.  When she clicks on the link, the movie starts playing in her browser and there is no easy way for her to save the file to disk. This is because her browser has been set up to play Quicktime files directly in the browser.

Another example is you send someone a Microsoft Word document and it shows up as gibberish in her browser. This is because her browser is trying to display something it doesn't know how to handle.

You can solve both problems by letting FileChute wrap your file(s) in a zip, tar or dmg file (you can select your preferred archive type under Preferences).