Write an iPhone & Android application

I need an application developed for iOS and Android smartphones of all sized (tablets excluded). Functions: The app will be very basic and has <about> 15 "functions". Each function presents the user with a FORM to populate with information (some free text, some drop downs). Once the form is populated and validated (i.e. required fields, email is actually an email, etc), the user will tap "submit" and the app must send the contents of that for to a predefined email address as a plain text email. * There is no login/account functionality required. so no backend at all just form, submit results in plain email to user. The catch is that the user is NOT allowed to see this email, so you cannot user the build in email app or any user email account - This is the trick. And you must be able to verify that the email was send, so you can display a confirmation message to the user. Design: I will provide all designs in .sketch format. Scaled to iPhone 6. It is your responsibility to scale to other screen sizes. These designs will be highly detailed and they must be pixel perfect. The app might be super simple format, but the design must stand out.. iOS and Android The app must work on both platforms and delivery must be the full source that can be deployed on my account to the app stores. I will own the source code after delivery. I am not set on native development, if you have an approach to use alternative technology to develop for both platforms, please suggest your best in the offer. Your offer Please include; 1. Native/other approach 2. you have .sketch? 3. understand the brief outline here 4. Happy to scale to other device sizes 5. Delivery timeframe 6. Any questions