What is Email Encryption?
Email encryption is the process of encoding email messages and attachments so that only the intended recipient can read them. It protects sensitive communications from interception, unauthorized access, and data leakage in transit or at rest.
What it does
Email encryption converts message content and attachments into ciphertext before transmission. Only a recipient with the correct decryption key can read the original message. Products in this category typically work in one of two ways:
- Gateway encryption: A server-side appliance or cloud service encrypts outbound mail automatically, often without requiring the sender to do anything extra.
- End-to-end encryption (E2E): The message is encrypted on the sender's device and decrypted only on the recipient's device. The mail server never sees plaintext.
Common standards include S/MIME, PGP/OpenPGP, and TLS. Some products use proprietary methods such as encrypted links or custom attachment formats to avoid relying on SMTP infrastructure entirely.
Why teams buy it
- Regulatory compliance: HIPAA, CMMC, ITAR, GDPR, and similar frameworks require protection of data in transit. Healthcare, defense, and financial organizations are frequent buyers.
- Controlled Unclassified Information (CUI): Defense contractors must encrypt email containing CUI before sharing it externally.
- Reducing SMTP risk: Standard SMTP can expose message content. Some tools bypass SMTP entirely to close that gap.
- Attachment protection: Encrypting files before they leave the sender's device prevents exposure even if the email is intercepted.
What to look for
- Key management: Who holds the keys? Customer-managed keys give more control. Vendor-managed keys are easier to deploy but create a dependency.
- Recipient experience: Can external recipients decrypt without installing software? Portal-based or link-based delivery lowers friction.