JHPeng's Blog：宏觀篇。

Intent emailIntent = new Intent(android.content.Intent.ACTION_SEND);
    emailIntent.setType("jpeg/image");
    emailIntent.putExtra(android.content.Intent.EXTRA_EMAIL, new String[]
    {"me@gmail.com"});
    emailIntent.putExtra(android.content.Intent.EXTRA_SUBJECT,
    "Test Subject");
    emailIntent.putExtra(android.content.Intent.EXTRA_TEXT,
    "go on read the emails");
    Log.v(getClass().getSimpleName(), "sPhotoUri=" + Uri.parse("file:/"+ sPhotoFileName));
    emailIntent.putExtra(Intent.EXTRA_STREAM, Uri.parse("file:/"+ sPhotoFileName));
    startActivity(Intent.createChooser(emailIntent, "Send mail..."));

http://stackoverflow.com/questions/587917/trying-to-attach-a-file-from-sd-card-to-email