Couchdrop has developed a simple way to send email attachments directly into specific folders within the likes of Dropbox, Box, GoogleDrive, AWS S3, Azure Files etc.
Navigate to Inboxes within Couchdrop and Create Inbox
Provide the inbox a Name, specify the folder where the files will be placed and enable email upload, you can also whitelist emails or email domains i.e. email@example.com or *@customeralpha.com. Save Settings once configured.
All you have to do now, is email your attachments to the email address with no subject line required and you will find your attachments as files within your selected folder.