You can secure your Dropbox Fax API callback url in two ways:
- Implement Basic Auth
- This would be something like https://username:password@your.domain/callback
- Note that basic auth credentials are redacted on Dropbox Fax's side
- Whitelist IPs from Dropbox Fax
- Ask support@hellosign.com for the outbound IP addresses from Dropbox Fax's API
Learn more about callback events.
Learn how to send a fax using the Dropbox Fax API.
