I can’t recommend a specific service to receive and scan mail, but if I were choosing one, I’d be more concerned about the integrity of its employees, its relia

I can’t recommend a specific service to receive and scan mail, but if I were choosing one, I’d be more concerned about the integrity of its employees, its reliability and longevity, and its compliance with postal regulations (e.g., in the U.S., requiring every customer to submit PS Form 1583, Application for Delivery of Mail Through Agent) than with the availability of source code for its software or its use of cryptography. You don’t want to lose mail or have to change your address if the service loses its lease, goes out of business, is closed by the Postal Service, or has its premises or data seized because another customer is suspected of criminal activity. As for privacy, you could have the service discard the junk and forward the remaining mail to you unopened, so its employees never see the contents and don’t create scans that might be considered business records subject to subpoena. Remember, too, that the U.S. Postal Service already images the outside of most letter-sized mailpieces, originally for OCR technology development and security reasons, and now also to provide the Informed Delivery service.