What is Certum Email ID Certificate - S/MIME? Certum is one of the biggest public certification authorities from Europe, by using the S/MIME certificate, it can encrypt email communication and provide digital signatures to protect your email privacy, preventing potential leakage and modification of email contents, it also verifies the authenticity of your identity to the recipient. Nowadays, remote work is becoming the norm for office employees, so it is important to ensure the security of email communication. Certum S/MIME certificate also supports a variety of emails, browsers, applications, and Microsoft operating systems.

S/MIME is also email encryption, it allows you to prevent email from being intercepted and ensure the security of email content. S/MIME provides digital signing and encrypts to effectively protects the company’s tradinge and commercial documents that are sent or received through email.It is used for users and enterprises that use emails to exchange sensitive datas, iIncluding government data, medical records, etc. S/MIME can secure your email exchanges both within and outside the organization.

Digital signature is attached to an electronic document to identify and verify the identity of the signer and the authenticity of the document. The digital signature is completely related to the sender and the content of the transmission. The sender is undeniable and cannot be forged by others, and it can be authenticated by a third party.

S/MIME - Certum Email ID Certificate

Solution

S/MIME - Individual

Application and Trial

US$13.3/Year

US$13.3 Year

Client authentication
Email signing
Email encryption
Verify email source
Prevent email tampering
Fast issuance
GDPR compliant
WebTrust standard
Verification time: 15 minutes to 1 hour
The data contained in the certificate: email address

S/MIME - Certum Email ID Certificate

You need the S/MIME certificate when professionalism, privacy, and business credibility matter！

What is S/MIME?

S/MIME (Secure/Multipurpose Internet Mail Extensions) is a security protocol for emails that ensures confidentiality, integrity, and authentication through digital signatures and encryption.

Key Features of S/MIME

Encryption：Ensures only the intended recipient can read the email, preventing third-party interception.
Digital Signature：Guarantees the email has not been altered during transmission and verifies the sender’s identity.
Authentication：Uses Public Key Infrastructure (PKI) to confirm that emails come from a trusted source.
Integrity Protection：Ensures email content remains unchanged and free from tampering.

Why Choose Yuan-Jhen’s Certum S/MIME Certificate

Largest Certification Authority in Europe：Certum is one of the biggest certification authorities in Europe, offering cost-effective, high-value solutions.
High-Level Security：Certum utilizes RSA 2048, ensuring strong encryption with minimal key length for optimal security.
Fast & Easy Setup：No additional software installation is required, and the setup process is simple and convenient.

S/MIME Email Encryption

Protect every email with industry-standard encryption and digital signatures. S/MIME keeps your confidential data—like business documents, financial info, and medical records—safe from interception. Perfect for businesses, governments, and professionals who can't afford email risks.

S/MIME Email Digital Signature

Build trust with every email you send. S/MIME digital signatures prove your identity and verify message integrity—so recipients know the email is truly from you. Backed by strong encryption, it stops spoofing, phishing, and tampering, making it a must-have for secure business communication.

Who Needs a Certum S/MIME Certificate?

✔ Companies requiring high email security

✔ Institutions handling confidential data (e.g. legal, financial, medical)

✔ Professionals aiming to prevent phishing attacks

✔ Security-conscious users on a budget

S/MIME Setup Guide & FAQs

How Does Email Encryption Work?

Email encryption converts email content into ciphertext using cryptographic techniques, ensuring protection against interception, modification, eavesdropping, or leaks during transmission. Encryption certificates, such as S/MIME, provide both encryption and digital signing services, ensuring secure email communications. S/MIME certificates are issued by trusted Certificate Authorities (CAs), guaranteeing email security.
Learn more about email encryption

How Does Email Digital Signing Work?

A digital email signature is a method of verifying the sender’s authenticity and includes additional encryption layers for enhanced security. It confirms the email’s legitimacy and sender identity, preventing spoofing, phishing, and email fraud. Digital signatures contain sender details such as name, position, company, and contact information, issued by a third-party certification authority (CA).
Learn more about digital signatures

How to Apply for an S/MIME Certificate?

Follow these steps to apply for and configure your S/MIME certificate. Click the button below for a step-by-step tutorial with images.

Step1. After purchasing the S/MIME certificate, log in to Yuan Jhen’s customer portal to configure and issue your certificate.
Step2. Generate a CSR and private key. Navigate to "Support" → "S/MIME CSR Generator" and enter your owner details in English. Store the private key securely and submit the CSR in the customer portal under "Provide new CSR to Renew."
Step3. Go to the "Show Certificate" page, paste the CSR into the provided field, and click "Get details from CSR" to auto-fill the certificate details.
Step4. Enter the Administrative Contact Information in English. Future renewal reminders will be sent to this email.
Step5. Submit the application and wait for the Certificate Authority (CA) to verify and issue your certificate.
Step6. Once issued, return to the customer portal, navigate to "Show Certificate," and copy the public key and intermediate certificate.
Step7. Merge the .crt and .key files into a .pfx file. This process generates a password—be sure to store it securely. You can use Yuan Jhen’s "PKCS12 Generator" for this step.
Step8. Copy the X.509 Certificate into the "Certificate" field, Intermediate Certificate into "Chain Certificate," and Private Key into "Private Key." Your S/MIME certificate will be delivered to your email.
Step9. Open the .pfx file and import the S/MIME certificate into your email client.
S/MIME Application & Setup Guide

How to Set Up S/MIME in Outlook?

Follow these steps to install an S/MIME certificate in Outlook. Click the button below for a detailed tutorial with screenshots.

Step1. In Outlook, go to File → Options → Trust Center → Trust Center Settings → Email Security → Import/Export.
Step2. Check "Import existing digital ID from a file" → Click "Browse" → Select your S/MIME .pfx file.
Step3. Enter the PKCS#12 password (generated when merging .crt and .key into .pfx) → Click "OK."
Step4. Go to Encrypted Email → Click Settings → Enter a Security Settings Name → Click Choose under "Signing Certificate" and select your certificate.
Step5. Set the Hash Algorithm to SHA256.
Step6. Click Choose under "Encryption Certificate" and select the same certificate as your signing certificate.
Step7. Verify your default S/MIME settings in the "Encrypted Email" section → Click "OK" to complete the setup.
Step8. When the recipient receives your email, they will see the S/MIME certificate icon and digital signature.
Outlook S/MIME Installation Guide

How Do Email Encryption & Digital Signatures Appear?

Emails using S/MIME certificates will display a certification seal in the recipient’s inbox, enhancing trust and corporate credibility.

Clicking the security certification will show email authentication details.

Common Email Scams & How S/MIME Prevents Email Fraud

Cybercriminals use phishing and Business Email Compromise (BEC) scams to impersonate individuals or companies, tricking recipients into revealing personal data or making fraudulent payments. Such attacks damage both individuals and businesses.

Just as websites need SSL security certificates, emails require S/MIME certificates to ensure secure transmission. S/MIME provides a digital signature that appears in emails, increasing visibility and trustworthiness in business communications.

Learn more: How S/MIME helps prevent email fraud