If you are scanning important, sensitive documents with your cell phone and sending those files over the internet, make sure to use an app from a reputable, reliable company. Do not use apps from relatively unknown developers, where images could potentially be intercepted. On Android phones, use Google Drive's scan option. On iPhone, open the Notes app and hit the + sign, then tap the "Scan Documents" option. Evernote Scannable is also a legitimate high-quality (free) scanning app. Overall, just be very careful how you handle private documents over email, as attached files can be forwarded to thousands of people against your will.