---
type: concept
title: Mozilla Thunderbird S/MIME Usage
tags: [smime, email-security, thunderbird]
related: [smime, e-mail-sicherheit, thunderbird-certificate-import]
created: 2026-06-30
updated: 2026-06-30
sources: ["output/rz_uni_greifswald_de_dienste_allgemein_e_mail_e_mail_sicherheit_cert_thunderbird.md"]
---

# Mozilla Thunderbird S/MIME Usage

The operational workflow for ensuring email security in [[mozilla-thunderbird]] using the S/MIME protocol involves two distinct processes: automatic signing and manual encryption.

## Operational Workflow

### 1. Digital Signing (Automatic)
After the successful completion of [[thunderbird-certificate-import]], Mozilla Thunderbird is configured to sign emails automatically. 
- **Effect**: This makes the email "tamper-proof" (fälschungssicher), allowing the recipient to verify the sender's identity and ensure the content has not been altered.

### 2. Encryption (Manual)
Unlike signing, encryption is not automatic and must be explicitly triggered by the user.
- **Action**: The user must select the **Verschlüsselung** (Encryption) button in the composition menu.
- **Visual Indicator**: A small **lock icon** appears in the subject line, confirming that the email is encrypted and "unbreakable" according to current technical standards.

## Configuration and Management
General S/MIME settings and functions are managed via the **S/MIME** button located in the Thunderbird menu.

## Summary Table: Signing vs. Encryption in Thunderbird

| Feature | Trigger | Purpose | Visual Indicator |
| :--- | :--- | :--- | :--- |
| **Digital Signature** | Automatic (post-import) | Authenticity & Integrity | (Standard S/MIME indicator) |
| **Encryption** | Manual (Encryption button) | Confidentiality | Lock icon in subject line |