"File" NOT "App"... can't be opened because it is from an unidentified developer got an mp3 via email from a musician friend of mine today. when i try to open it (in any app... itunes, quicktime, vlc, etc), i get this message as if it's a new Application that i just downloaded from the internet.

i KNOW what to do if it's an app (keep my system prefs security settings &amp; secondary-click on it &amp; choose open that way) that i trust, but i've never experienced this happening before with "Files" that i trust.

is this normal &amp; safe to open as if it was an app? or could something have happened to it &amp; opening could be bad? or could it have been intercepted &amp; actually be some sort of trojan or something?
I have two guesses:


It is an application masked as an mp3 file. Yes, you should not open it.
Mac OS X gives warnings "blabla downloaded from internet" for anything, not just apps downoaded from Internet. If you are sure the file is fine, play it back.


By the way, mp3 files must be able to play back by just quick previewing them (Space bar).