Documents you email are sent from the account set up in your phone's email app. Here's how to send from a different address.
On iOS
Add the email address you want to use to the Mail app - see Apple's guide to adding an email account
To make it your main sending address, open your phone's Settings > Mail > Default Account and select it. On newer iOS versions, Mail is under Settings > Apps.
You can also switch between accounts each time you send a document
On Android
The app sends through Gmail when you have more than one email app installed
To send from another address and keep using Gmail, add that address to Gmail - see how to add another address to Gmail
Send with Gmail or Outlook instead
When sending a document, tap Send > Other
Choose Gmail or Outlook
Didn't find what you were looking for? Contact our support team, and we'll sort it out for you.