---
title: "S/MIME"
canonical_url: "https://www.zone.eu/support/kb/smime-2/"
post_type: "ht_kb"
published: "2022-08-09T11:50:15+00:00"
modified: "2026-05-18T06:37:16+00:00"
language: "en"
author: "sten"
taxonomies:
  ht_kb_category:
    - name: "Zone Webmail (web-based e-mail)"
      url: "https://www.zone.eu/support/kb-categories/zone-webmail-web-based-e-mail-en/"
    - name: "E-mail"
      url: "https://www.zone.eu/support/kb-categories/e-mail-en/"
  ht_kb_tag:
    - name: "S/MIME"
      url: "https://www.zone.eu/support/kb-tags/s-mime-en/"
---

# S/MIME

S/MIME (Secure/Multipurpose Internet Mail Extensions) is a standard for signing and encrypting e-mails end-to-end. Usually signing, verifying and encrypting/decrypting is done by the mail client.

Using S/MIME with your standalone email client such as Thunderbird, Outlook or Apple Mail is supported.

### S/MIME Support in Zone Webmail

Zone Webmail can verify the validity of incoming S/MIME signatures and display the signature status to the user.

[![](https://www.zone.eu/static/sites/5/s_mime_eng.png)](https://www.zone.eu/support/kb/smime-2/s_mime_eng/)

Signature validity is verified against the same root certificates as used in Thunderbird.

 Important! Zone Webmail cannot:
• sign emails
• encrypt emails
• decrypt encrypted emails.

S/MIME signing and encryption must be done in a separate email client, such as Thunderbird or Outlook.