If don't like browser playing an .mp3 file then don't use a client that auto-plays .mp3 files, or change browser settings so that this filetype does not auto-play.
It's like asking someone not to link to a PDF because it is "auto-displaying". If don't want PDF to display in browser then change browser settings so that it doesn't.
In the browser I use, I can associate any file extension with any MIME type. Even better, there is no built-in MP3 player, PDF viewer, or other omnibus cruft.