Secure Email – Native S/MIME vs Mail Gateways

Secure Email – Native S/MIME vs Mail Gateways
25 Oct ‘23

Ensuring the safety and privacy of sensitive information in your email communication is of utmost importance in today’s digital landscape. With the rising threat of cyberattacks, both individuals and businesses are actively seeking robust email encryption solutions. Let’s explore two popular options for securing email content: native email encryption using S/MIME (Secure/Multipurpose Internet Mail Extensions) and email encryption gateways based on S/MIME. Each approach has its unique advantages and disadvantages that you should consider.

Native Email Signing and Encryption using S/MIME


  1. Seamless Integration: S/MIME seamlessly integrates with many popular email clients, making it convenient for users to send and receive encrypted emails without the need for third-party applications.
  2. Strongest Security: S/MIME employs digital certificates and asymmetric end-to-end encryption to provide robust security measures, ensuring the maximum protection of sensitive data’s integrity and confidentiality from the senders device to the receivers device.
  3. User Control: Users have direct control over the encryption process, allowing them to manage their keys and digital certificates independently, or leaving this to company admins to handle using tools like MS Intune.
  4. Ease of use: Digitally signing of email or full end-to-end protection is very easy for any user, simply choose the options ‘Sign’ and/or ‘Encrypt’, knowledge of encryption protocols is not required.


  1. Complex Setup: Configuring S/MIME encryption can be complex, particularly for users unfamiliar with cryptographic technologies. This complexity leads to implementation challenges, which can be overcome using the KeyTalk Certificate & Key Management System (CKMS) that can fully automate the request, enrollment, mail client configuration and management of the S/MIME certificates.
  2. Limited Interoperability: S/MIME may encounter interoperability issues when communicating with users who lack the necessary certificates or use email clients that do not support S/MIME encryption. KeyTalk can empower your users to distribute S/MIME certificates to third parties without certificates.

Email Encryption Gateways

Email encryption gateways act as intermediaries between senders’ and recipients’ email servers. These gateways automatically apply encryption to outgoing emails based on predefined security policies, ensuring the protection of sensitive information during transmission.


  1. Simplified Deployment: Email encryption gateways can be implemented organization-wide, offering a centralized solution for all users, regardless of their email clients. IT administrators can manage the process, simplifying deployment.
  2. Improved Interoperability: Email encryption gateways facilitate communication between users with varying encryption capabilities, ensuring secure communication even when recipients lack specific encryption setups.


  1. Less secure; Even though the same form of encryption is used, the email message from the sender is send unencrypted from the user’s device to the email gateway and therefore readable to any ‘hacker’ within the sender’s network, only upon arrival, the message is encrypted. Proof of message integrity cannot be ensured, as it can with standard use of S/MIME.
  2. Dependency on Third-Party Services: Using email encryption gateways involves relying on third-party services. This may raise concerns about data privacy and security in cases where the gateway provider’s infrastructure is compromised.
  3. Recipient Limitation: Email encryption gateways might only work for either inter-company or intra-company email, not both.
  4. Audit and Compliance Issues: Encrypted emails stored on the encryption gateway may cause audit and compliance issues. Recipients may need to store a copy of email content on a central archive or back up messages locally, impacting compliance.
  5. Additional Hurdles for Recipients: Reading encrypted emails received via an encryption gateway may require additional login steps or extra apps on mobile devices, potentially making it more challenging for some recipients.
  6. Potential Latency: Introducing an additional layer for email encryption may lead to slight delays in email delivery, which could affect time-sensitive communications.


Understanding the differences between native email encryption using S/MIME and email encryption gateways is vital when choosing the right option for your specific needs. Whether you prioritize user control and security with S/MIME or seek a centralized solution with enhanced compliance through an encryption gateway, evaluating the pros and cons is essential for effective email security.

Please contact us and we can discuss your challenges with digital email signing and encryption using the world standard for more secure email S(ecure)/MIME.

The KeyTalk team