Many do not know it, but regular email is now illegal email for this:
- Health plans, doctors, hospitals and other health care providers. (The American Health Insurance Portability and Accountability Act HIPAA makes these entities protect patient account handling, billing and medical records. Section 164.306 requires them to use transmission security, integrity control and encryption.)
- Financial institutions, lending, brokering, auditing, transferring or safeguarding money, preparing tax returns, providing financial advice and credit, real estate settlement services, collecting consumer debts and more. (The Gramm-Leach-Bliley Act controls how they handle and process individual non-public private information. It emphasizes protection and related administration, technical and physical safeguards.)
- Attorneys, brokers or dealers, investment bankers, security companies handling electronic transactions, non-American companies with such operations in U.S., auditors and firms that review and report on financial statements, public companies and private firms that may become public. (The Sarbanes-Oxley Act affects their financial practice and corporate governance. It protects investors by improving the accuracy and reliability of corporate disclosures under securities laws.)
Digital signatures provide a way to verify that the sender is who they claim to be. It is easy to forge from-addresses in emails. You may notice this due to viruses and spam from senders that did not send it. Say Alice sent an email to Bob, claiming to be Charlie. She made some comments that made Bob react against Charlie. He got a reprimand or lost his job. You can avoid this by integrating digital signatures.
That is why we use Dropbox, not illegal email.