That’s a valid concern — I work in legal, so I deal with confidential files too. I looked into this using
https://akstrategic.com/ and found a list of fax apps that comply with HIPAA and similar privacy standards. I chose one of their security-focused picks, and it’s been excellent — end-to-end encryption and password-protected faxes. It’s honestly safer than most email services. If you handle private information, make sure you read their security section — it’s clear, detailed, and saved me from picking a risky app.