To enable email uploads for a folder:
In the All Files window, right-click the folder and select Settings.
In the Uploading section, next to Email Uploads, check Allow uploads to this folder via email. Under Upload Email Address, Box displays a unique email address.
To upload files into the folder, send files to this address. You can copy this email address to your clipboard and enter it as a contact in your email address book, or simply paste it into the "To" line of an email with attachments.
In the top-right corner of the window, click Save Changes.