Add-ons
Mail-Guard 0.8.7
by Michael
Warns when opening an email if the sender, links or attachments look unsafe. Everything runs locally. Suspicious emails can be reported to your own IT, newsletters from senders can be unsubscribed, and you are warned before replying to forged emails.
About this Add-on
Mail-Guard is a privacy-focused security add-on for Mozilla Thunderbird (v115+) that automatically analyzes incoming emails when opened and displays a warning banner if suspicious senders, links, or attachments are detected. All analysis is performed 100% locally on your device. It features zero telemetry and never transmits emails or user data to external servers.
Key Features & CapabilitiesVisual Safety Banners:
Red (Warning): Severe phishing or security risks (e.g., impersonated internal senders, deceptive link targets, executable attachments).
Yellow (Caution): Potential anomalies (e.g., mismatched reply-to addresses, shortened URLs, urgency keywords combined with freemail domains).
Comprehensive 3-Way Inspection:
Sender Check: Detects typo-squatting, impersonation of colleagues, display name spoofing, and failed SPF/DKIM/DMARC checks.
Link Check: Inspects target URLs for manipulation (e.g., IP addresses as links, lookalike domains, hidden credentials). Links are inspected locally and never opened/resolved.
Attachment Check: Flags dangerous files (.exe, scripts), double extensions (e.g., Invoice.pdf.exe), macros, or obfuscated characters.
Report Suspicious Email (IT Security):
Generates an incident report to your internal IT security team with a single click. Strict rules restrict reporting strictly to internal domain addresses.
Safe Newsletter Unsubscribe:
Handles List-Unsubscribe headers securely via HTTPS links or pre-drafted emails, preventing automated tracking.
Pre-Send Warning:
Prompts a confirmation window if you attempt to reply to an email previously flagged as dangerous.
Full Customization & Enterprise Ready:Configurable internal and trusted external domains.
Customizable detection lists (brand names, keywords, urgency rules).
Supports central deployment and management via group policies.
Key Features & CapabilitiesVisual Safety Banners:
Red (Warning): Severe phishing or security risks (e.g., impersonated internal senders, deceptive link targets, executable attachments).
Yellow (Caution): Potential anomalies (e.g., mismatched reply-to addresses, shortened URLs, urgency keywords combined with freemail domains).
Comprehensive 3-Way Inspection:
Sender Check: Detects typo-squatting, impersonation of colleagues, display name spoofing, and failed SPF/DKIM/DMARC checks.
Link Check: Inspects target URLs for manipulation (e.g., IP addresses as links, lookalike domains, hidden credentials). Links are inspected locally and never opened/resolved.
Attachment Check: Flags dangerous files (.exe, scripts), double extensions (e.g., Invoice.pdf.exe), macros, or obfuscated characters.
Report Suspicious Email (IT Security):
Generates an incident report to your internal IT security team with a single click. Strict rules restrict reporting strictly to internal domain addresses.
Safe Newsletter Unsubscribe:
Handles List-Unsubscribe headers securely via HTTPS links or pre-drafted emails, preventing automated tracking.
Pre-Send Warning:
Prompts a confirmation window if you attempt to reply to an email previously flagged as dangerous.
Full Customization & Enterprise Ready:Configurable internal and trusted external domains.
Customizable detection lists (brand names, keywords, urgency rules).
Supports central deployment and management via group policies.
