According to HT4622 you can copy audio into GarageBand from an app that supports copying audio to the clipboard. Once in GarageBand it would possible to make edits such as trimming or removing/repeating segments. You could then "share" the resulting song via email.
What kind of recording are we talking about? GarageBand has a maximum song length of 32 minutes (320 bars at 40bpm) which may affect its suitability for your project.