Android Share XML file in mail with specific file extension

Hi I need a small prototype that may lead to the full project later. Kindly provide an estimation for the time and money. Should be easy job . Functionality needed: 1. App converts a sample XML string to a Custom file format ( extension .xyz or any) . 2. User can send this in mail with attachment like we send zip, etc. 3. Receiver opens the file 4. When attachment preview is clicked in the mail , the link takes it to the app 5. The app decompresses and open the XML string and save it in an xml file inside the app. Due to XML size, standard Gzip compression should be considered while sending the attachment. i.e. compressing and decompressing the XML content.