iso-8859-1 charset + base64 CTE on HTML body (encoding evasion)
charset-downgrade-iso88591-abuse
What this tier means
High-confidence threat indicator — phishing, impersonation, BEC, or scam pattern. Strong contributor to the trash decision.
How Gorganizer detects this
Encoding evasion: the email declares a legacy charset (iso-8859-1, windows-1252, or cp1252) in the Content-Type header AND uses Content-Transfer-Encoding: base64. Modern HTML email is always UTF-8; deliberately downgrading to a legacy charset combined with base64 encoding is a known technique used by spam toolkits to hide promotional keywords from UTF-8-aware content scanners. Only fires when the email body also contains tracking parameters (utm_source, utm_campaign, utm_medium), unsubscribe links, or 2+ promotional keywords (special offer, % off, limited time, etc.). Not applied to known invoice, work, or shopping senders. Score: +2.
False-positive guard
Every signal in Gorganizer feeds a multi-module score — never a sole verdict. This is a threat-tier signal — it adds a strong contribution to the trash score. The full pipeline still requires convergence across multiple modules + a margin over the safety floor before deletion happens, and Gmail's trash (30-day recovery) is always used — never permanent delete.
About the scoring engine
Gorganizer's scoring engine emits over 1,800 signals across six modules — headers, sender, subject, body, attachments, and structural metadata. Every email is scored by every module independently; the final verdict requires multiple modules to agree and the trash score to beat the safety floor by a margin.
Sacred safety guards — never delete starred emails, replies, calendar invites, receipts/invoices, or attachments — apply unconditionally regardless of any signal.
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