Simplest way is to use
Thread.setDefaultUncaughtExceptionHandler
In your main activitys onCreate. This will catch all exceptions not handled by a try catch block. I also recommed sending an lightweight error-report to your server with the stacktrace. This way you can aggregate all crashreports and fastly see where your code is buggy. You will get almost all force-closed reported. I dont think using email is a good idea, as 100 of emails are not so easy to handle, count etc... also Its abit "raping" your user, since he never have asked for sending any emails, He does not even have a clue what its about, unless he is a java developer...
So, don't bother the user with error-reports if you can avoid it.