For Windows
MP3myMP3 Recorder saves any audio you hear on your computer straight to mp3 or wav. If you can hear it you can record it! Record internet radio and save to mp3 or wav. Record from any source. Rip Vinyl, rip CD's, batch rename, create playlist and more. It makes an exact digital copy of what you hear.
This program is distributed as freeware. It works good on Windows.
For Linux I use Sound Recorder which does the same as MP3myMP3 Recorder only is easier to use.
Have no idea how to embed music into an outgoing email.