Note: Have you used an E-mail ID before and want to renew the certificate? - choose the new Certum SMIME, get issued, and continue using secure mail. If you have any questions, contact the hotline at + 48 91 4801 340 or send an email to: Read more ↗

Certum S/MIME Mailbox

Join the reliable Internet users! Conducting secure and personal electronic correspondence has never been so safe.

Thanks to the S/MIME Mailbox certificate you can:

  • authorize your email address,
  • encrypt, sign and authenticate your personal email,
  • protect your emails and attachments against falsification.

Key features of the S/MIME Mailbox certificate:

  • contains email address of the user
  • automatic issue within a few minutes

Have you ordered E-mail ID Individual (S/MIME) before? – this variant is for you!

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Certum S/MIME Mailbox

Certum S/MIME Mailbox – the highest level of security guaranteed by proper email address verification

A mailbox certificate is the simplest and most basic type of S/MIME digital certificate, which is used to authenticate the sender's email address and encrypt and sign emails.

Mailbox certificates are used for personal and business email accounts. Note, however, that they only authorize an email address.

Their primary advantage is their quick and automatic release (up to 5 minutes) after email address verification.

Key Features of S/MIME Mailbox certificate

  • Encrypts messages
    The certificate encrypts the content of emails, which protects them from being accessed and read by others who are not the correct addressee.
  • Protects the content
    The digital signature in the certificate confirms that the message has not been altered during its transmission to the recipient.
  • Signs digitally
    The digital signature of an email allows recipients to verify its origin and check the certificate at any time.
  • Informs recipients
    All emails signed with the certificate are highlighted with a cotillion icon in the recipient's inbox, enhancing the sender's reputation among the recipients of the communication.
  • It is compatible
    Supported by many popular email clients, such as Microsoft Outlook, Mozilla Thunderbird, Apple Mail, this allows S/MIME certificates to be used in a variety of environments and platforms.

Why use S/MIME Mailbox certificate?

S/MIME Mailbox provides mailbox users with greater security and confidentiality of email communications and protects against various types of attacks and abuse.

  • Confidentiality and integrity of data
    Encryption ensures that only the right recipient will read the message, and that unauthorized people will not learn its contents. The certificate confirms that the message was not tampered with during transmission.
  • Authenticity and protection
    By digitally signing emails, the recipient can be sure who the sender is, and the certificate protects against fraud, impersonation, forgery and phishing.
  • Credibility of the sender
    The certificate increases credibility and trust in the business community. By sending encrypted and digitally signed messages you ensure the security and confidentiality of your communications.
  • Regulatory compliance
    The use of the certificate helps achieve regulatory compliance. In some industries, such as finance or healthcare, there are regulations regarding data security and confidentiality.

Certum S/MIME Mailbox is compliant with all current regulations and meets stringent requirements.

  • Contains email address of the user
  • Automatic issue within 15 minutes of clicking on the link in the verification email
  • It is compliant with the X.509 v.3 (RFC5280) standard
  • It is secured with SHA2 function
  • Minimum length of cryptographic keys: RSA/DSA 2048 bit
  • Supported cryptographic cards: cryptoCertum 3.0, cryptoCertum 3.2, cryptoCertum 3.5 and cryptoCertum 3.6
  • Issued by Certum PCC in line with international WebTrustSM/TM standard
  • Issued by Certum PCC, whose certificate root is automatically recognized as trusted in all the most popular Internet browsers as well as in all Microsoft products
  • Verification of the certificate status with the use of CRL lists and OCSP protocol is possible,
  • Security level: Guarantee of the highest level of security
  • Support for email clients: Mozilla Thunderbird, Outlook, Hotmail, Mail, The Bat
  • Support for web browsers: Web browsers that support X509 v.3 certificates (e.g. Internet Explorer, Opera, Firefox)
  • Operating systems: Windows 7, 8, 10; OS X
  • RSA keys allow both message signing and encryption, whereas EC (Elliptic Curve) keys only enable message signing without the capability for encryption.
    NOTE: If you want to encrypt emails, generate a certificate with RSA keys

The Certum S/MIME Mailbox certificate is automatically issued based on the user's verification of the email address. Certum does not require any additional documents from the user. As a result, it takes a maximum of 15 minutes to issue the certificate. You receive it after clicking on the link in the message we send in the process of certificate activation to the email address you provided. More information on

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