The Send button is inactive when I try to email a scanned document
When you try to export your documents via email, the "Send" button can be inactive. This indicates that Apple's Mail app isn't properly configured.
Make sure the Mail app is installed
Go to the Home screen and verify that the Mail app appears in your app launcher.
If the icon doesn't appear anywhere, the Mail app needs to be enabled from the app store (cf. Mail app page)
Check the configuration of your email account account
Open Apple's Mail app, and verify that an email account has been properly configured. Here's a step-by-step guide on how to set up email accounts on iOS devices.
If you are able to send and receive emails with the Apple's Mail app, you can troubleshoot remaining issues in this article.