How do I download a Google Colab notebook?
You do not need to download Google Colab to send a file through email.
To send directly:

On Upper right-hand side there is a share button, Click on it.
A pop-up appears, Enter email addresses or usernames in the field 'Add People and groups'.
(Optional) Go to the setting gear button upper right corner and adjust permissions.
Click on 'Done'.

Download then send to email:

Click on the &quot;File&quot; menu in the upper left corner.
A popup appears, find 'Download .ipynb' and click on it.