Some ISPs put tight restrictions on the size of email messages their
customers can receive. If you've tried sending this file to someone in
particular you will have received a bounce message, which will probably
indicate the maximum file size they can receive. One option is to compress
that music file further so that it will match those restrictions, but that
will degrade audio quality.
Another option is to open a free account with someone like Yahoo Briefcase
http://briefcase.yahoo.com/ and upload the file to your account, then send a
link and your password to your recipient. Yahoo has a maximum single file
upload of 5MB which is larger than most ISPs will let you send via email,
but it's a bit of a pain in the ass to use this approach.
A better option may be to send the file via an Instant Messenger program.
Connect to each other and send the file. If you're both running Windows you
both probably have MSN Messenger installed, and there aren't any file size
restrictions to worry about. I've sent full albums to my brother using
Messenger.
HTH,
Ian.