Email Delivery Guide

Email Security

Protecting Email Communication

Email security is essential for protecting sensitive information and ensuring the integrity of your communications. Without proper security measures, emails face numerous threats including eavesdropping, tampering, and identity theft.

Common Email Security Threats

  • Message Tampering: Emails can be modified by anyone with system-administrator access to SMTP servers
  • Repudiation: Senders can deny sending messages, as emails can be easily faked
  • Eavesdropping: Unsecured emails can be captured and read by third parties
  • Privacy Invasion: Email transmission can reveal sensitive information like IP addresses
  • Unprotected Backups: Unencrypted messages stored in plaintext on servers and backups
  • Identity Theft: Login credentials can be captured if email servers aren't accessed securely

TLS Email Encryption

Transport Layer Security (TLS) provides an encrypted tunnel for email traffic between servers. See how TLS protects your emails during transmission:

Alice
Sender
Email Client
TLS Enabled
Alice's Server
Internet
Bob's Server
Bob
Recipient
Email Client
TLS Enabled

Alice composes an email to Bob

Step 1 of 9
TLS Encryption

SMTP TLS

Transport Layer Security provides an encrypted tunnel for email traffic between servers.

Key characteristics:

  • Protects emails during transmission
  • Simple to set up and use
  • Recipients don't need special configuration
  • Widely supported by email providers

S/MIME

Secure/Multipurpose Internet Mail Extensions enables both encryption and digital signatures.

Key characteristics:

  • Built into many email clients
  • Uses certificate authorities for verification
  • Provides both encryption and authentication
  • Popular in corporate environments

PGP

Pretty Good Privacy uses public and private key encryption for high security.

Key characteristics:

  • High level of security
  • Long history with broad user base
  • Open source options available
  • Works with most email accounts

S/MIME Email Encryption

Secure/Multipurpose Internet Mail Extensions (S/MIME) provides end-to-end encryption and digital signatures. See how S/MIME works with certificate authorities to secure email content:

Alice
Sender
Keys
Private
Public
End-to-End Encrypted
Certificate Authority
Bob
Recipient
Keys
Private
Public

Alice obtains an S/MIME certificate from a Certificate Authority

Step 1 of 9
S/MIME Encryption

How Email Encryption Works

Email encryption transforms readable text into encoded ciphertext that can only be decoded with the proper key. There are two main types of encryption used in email security:

Symmetric Encryption

Uses the same key for both encryption and decryption. This method is fast but requires a secure way to share the key.

Asymmetric Encryption

Uses a pair of keys: a public key for encryption and a private key for decryption. This eliminates the need to share secret keys.

Most email encryption systems use a combination of both methods: asymmetric encryption to securely exchange a symmetric key, then symmetric encryption for the actual message content due to its efficiency.

PGP Email Encryption

Pretty Good Privacy (PGP) is a powerful encryption system that provides high security through public key cryptography. See how PGP works to secure email content:

Alice
Sender
Keys
Private
Public
End-to-End Encrypted
Bob
Recipient
Keys
Private
Public

Alice and Bob both generate their own PGP key pairs

Step 1 of 9
PGP Encryption

Comparison of Email Encryption Methods

FeatureSMTP TLSS/MIMEPGP
Ease of UseHighMediumLow
Security LevelMediumHighHigh
Recipient Setup RequiredNoYesYes
Corporate AdoptionHighHighLow
Message Storage ProtectionNoYesYes

Best Practices for Email Security

  1. Use TLS for all email transmissions as a baseline security measure
  2. Implement S/MIME or PGP for sensitive communications requiring end-to-end encryption
  3. Verify digital signatures to ensure message authenticity
  4. Keep private keys secure and never share them
  5. Use strong passwords for email accounts
  6. Enable two-factor authentication when available
  7. Regularly update email clients and security software
  8. Train users on proper security practices and the importance of encryption