“I want to send a song in email to my friend, but when they get the file it says they can’t play it. How can I attach a song to an email and have it work when my friend gets it?”
Since most music files are no more than 3-5MB in size, sending them via email should work functionally. It sounds like attaching the file isn’t the problem, which simply requires clicking the attach a file button in your email program and choosing the song. There may be some kind of permissions issue happening when you try to send the song in an email message. Here are some things you can try to get around the problem.
Since it sounds like your friend is getting the song, this isn’t an issue of the attachment being too big for their email. At the same time, sending songs via email isn’t the most efficient way to share music. What you might try instead is searching for the song on YouTube and sending a link to the video your friend can listen to, or search on Last.fm for the song you want to send as a link. In either case, your friend will then be able to play the file instantly.
A second possible solution is that the format of the song on your computer isn’t compatible with anything your friend has to play it back. In that case, you may want to use conversion software to convert the file to .mp3, which should play anywhere. One solution is to convert the file to MP3. You then attach the .mp3 file to the email and send it instead of the original file.