If the attachment is in a supported file format, you can open the file in the app with these steps:
- View the attachment directly in the email app.
- Bring up the Share sheet on the file. For example:
- In Outlook, choose the Share icon > Share File via...
- In Mail, choose the Share icon.
- Choose Open in Goodnotes from the Share sheet.
Alternatively, you can simply save the attachment to your device, view the file in the Files app and share it with Goodnotes.