I had the same concerns before I started faxing from my phone. I found a detailed explanation on derekdubois.net that helped me understand which apps encrypt data and what settings protect your privacy. The site recommends apps that provide end-to-end encryption and automatic deletion of documents after sending. I tried one of the suggested apps, and now I can fax contracts and forms without worrying about leaks. The article also emphasizes avoiding public Wi-Fi and checking delivery confirmations. Following these tips made me feel confident that mobile faxing can be secure if you choose the right app and settings.