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Glossary

Email Encryption

Email encryption is the process of encoding email content so that only authorized recipients can read it. It protects sensitive information from interception during transmission (in-transit encryption) and from unauthorized access when stored on servers (at-rest encryption).

Key Aspects

TLS (Transport Layer Security)

Encrypts the connection between mail servers, protecting emails in transit. Used by most modern providers.

S/MIME

Uses digital certificates to encrypt individual messages end-to-end and provide sender verification.

At-Rest Encryption

Protects stored emails on servers and devices from unauthorized access if the system is compromised.

Types of Email Encryption

Transport Layer Security (TLS) is the most common form of email encryption. It secures the connection between sending and receiving mail servers, preventing eavesdropping during transit. Most major email providers enforce TLS by default, but it only protects the connection — not the message itself once it arrives on the destination server.

For stronger protection, end-to-end encryption protocols like S/MIME and PGP (Pretty Good Privacy) encrypt the actual message content. Only the intended recipient, who holds the private decryption key, can read the message. These methods are commonly used in healthcare, legal, and financial industries where message confidentiality is paramount.

Frequently Asked Questions

Is my email already encrypted?
Most major providers (Gmail, Outlook, etc.) use TLS to encrypt emails in transit by default. However, this only protects the connection between servers, not the email content itself. End-to-end encryption requires S/MIME or PGP.
Does email encryption affect signatures?
TLS encryption is transparent and does not affect email signatures. S/MIME encryption may affect how HTML signatures are rendered, as the encrypted content is handled differently by email clients.
Do I need end-to-end encryption?
It depends on your industry and the sensitivity of your communications. Industries handling personal health information, financial data, or legal privileged communication often require it.
What is the difference between S/MIME and PGP?
Both provide end-to-end encryption, but they use different key management approaches. S/MIME uses centrally issued certificates (common in enterprises). PGP uses a decentralized web of trust model (common among individual users and developers).

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