Email encryption with S/MIME: The standard for more data protection

Unencrypted emails are like postcards – anyone who intercepts them en route can read them. Nevertheless, confidential information is sent unprotected every day. Despite this, secure and proven methods like S/MIME have long existed for reliably encrypting and digitally signing emails. The proven S/MIME encryption technology protects emails, ensures their authenticity, and prevents tampering. But how exactly does S/MIME work, and what possibilities does this encryption offer in practice?

What is S/MIME?

S/MIME stands for Secure/Multipurpose Internet Mail Extensions and has been a globally recognized standard for email encryption and digital signatures for over 30 years. The goal is to ensure that only the intended recipient can read a message—and can be assured that it originates from the specified sender and has not been altered along the way. This technology also forms the basis of zertmail. – the email encryption service for companies that want to combine data protection and user-friendliness. How does S/MIME work? S/MIME is based on asymmetric cryptography and uses a key pair:

• Public key: Is shared to encrypt messages.
• Private key: Remains secret and is used for decryption and signing.

S/MIME is supported by most modern email clients such as Microsoft Outlook, Apple Mail and Thunderbird.

The process in three steps:

1. The email is encrypted with the recipient’s public key.
2. The recipient decrypts it with their private key.
3. Optionally, the sender signs the email with their private key to confirm its authenticity.

Why is S/MIME secure? 

• End-to-end encryption: Only the sender and recipient can read the contents.
• Integrity: Message tampering is reliably detected.
• Authenticity: Digital signatures ensure clear sender verification.
• Proven: S/MIME has been established as an industry standard for years, has been tested worldwide, and is compatible with common email clients.

S/MIME & Outlook: A powerful duo

Many email programs, such as Microsoft Outlook, already support S/MIME by default. This makes it easy to encrypt emails—provided you have a valid S/MIME certificate. Instructions for encryption in Outlook can be found in diesem Beitrag. zertmail. relies on S/MIME, but also offers a user-friendly interface via plugin, central certificate management, and modern integrations for daily use – especially for external communication with recipients without their own certificate.

Who has to encrypt emails in Austria?

Since the GDPR came into force, it has been clear: anyone who processes personal data must take technical measures to protect it – this includes email encryption. Affected are, among others:

• Healthcare facilities
• Lawyers, notaries, tax advisors
• Insurance and real estate agents
• Finance and purchasing departments
• HR departments and personnel managers
• Sales, customer service, and marketing with access to customer data
• IT administrators and support

The new EU directive NIS-2, which stipulates increased security standards for critical infrastructures, also obliges affected organizations to ensure secure communication – including encrypted emails. With zertmail., you not only meet the requirements of the GDPR, but are also well prepared for the upcoming NIS-2 regulations.

What should be considered when using S/MIME?

• Certificates must be renewed regularly (usually annually).
• Not all programs support S/MIME equally well.
• Using them can be cumbersome for recipients without a certificate.

zertmail. combines the proven security of S/MIME with modern usability – ideal for companies that want to integrate encryption easily and legally compliant into their daily work. zertmail. handles the complete administration and automatic renewal of S/MIME certificates, ensuring no additional effort for your IT department and ensuring secure communication at all times.

Conclusion: S/MIME is the standard – and zertmail is the best solution for it.

S/MIME is rightly considered the gold standard in email encryption. It reliably protects against data leaks and unauthorized access – and helps meet legal requirements. Use S/MIME encryption with zertmail. to communicate in compliance with GDPR, NIS-2, and GtelG regulations – simply, securely, and effortlessly. Would you like to finally make your email communication secure? Then zertmail is the right solution for your company. Jetzt Kontakt aufnehmen Are you an IT service provider or do you serve customers with high data protection needs? Become a zertmail. partner and benefit from special conditions: Mehr erfahren & Partner werden