Detection Method: Header analysis

Header analysis inspects the metadata in message headers to find suspicious patterns, anomalies, or inconsistencies that could indicate phishing, spoofing, or other types of malicious activity. It looks at various header fields like routing information, authentication results, and sender verification data to help spot potential threats.
This includes sender authentication headers like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) results to verify the sender's legitimacy. It also checks how the email traveled through mail servers, looking for any unusual routing that might suggest tampering.
Header analysis can detect:
  • Email spoofing, where attackers forge the sender’s address to appear legitimate
  • Mismatched or inconsistent sender details
  • Suspicious return paths that don’t match the expected sender
  • Unusual routing patterns that stand out from normal email flow
  • Authentication failures that signal potential impersonation attempts
For example, attackers might try to forge email headers to make phishing emails appear as if they’re coming from a trusted source like your bank or your company’s internal email. Header analysis helps you catch these attempts by identifying mismatches between the displayed sender and the actual sending server.
Rule Name & Severity
Last Updated
Author
Types, Tactics & Capabilities
Link: Personal SharePoint with invalid recipients and credential theft language
16m ago
Jan 23rd, 2026
Sublime Security
/feeds/core/detection-rules/link-personal-sharepoint-with-invalid-recipients-and-credential-theft-language-79d5403d
Brand impersonation: File sharing notification with template artifacts
16m ago
Jan 23rd, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-file-sharing-notification-with-template-artifacts-37d89611
Service abuse: Adobe legitimate domain with document approval language
15h ago
Jan 23rd, 2026
Sublime Security
/feeds/core/detection-rules/service-abuse-adobe-legitimate-domain-with-document-approval-language-237f4da4
Extortion / sextortion (untrusted sender)
20h ago
Jan 22nd, 2026
Sublime Security
/feeds/core/detection-rules/extortion-sextortion-untrusted-sender-265913eb
BEC/Fraud: Romance scam
23h ago
Jan 22nd, 2026
Sublime Security
/feeds/core/detection-rules/becfraud-romance-scam-0243cdaa
Brand impersonation: Dropbox
1d ago
Jan 22nd, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-dropbox-61f11d12
Callback phishing via calendar invite
1d ago
Jan 22nd, 2026
Sublime Security
/feeds/core/detection-rules/callback-phishing-via-calendar-invite-95c84360
Brand impersonation: AuthentiSign
2d ago
Jan 21st, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-authentisign-445a8c8b
Brand impersonation: Blockchain[.]com
2d ago
Jan 21st, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-blockchaincom-0d85e555
Link: Self-sent message with quarterly document review request
2d ago
Jan 21st, 2026
Sublime Security
/feeds/core/detection-rules/link-self-sent-message-with-quarterly-document-review-request-3c42cec6
Job scam with specific salary pattern
2d ago
Jan 21st, 2026
Sublime Security
/feeds/core/detection-rules/job-scam-with-specific-salary-pattern-af7f9e21
Impersonation: Internal corporate services
3d ago
Jan 20th, 2026
Sublime Security
/feeds/core/detection-rules/impersonation-internal-corporate-services-3cd04f33
Brand impersonation: Xodo Sign
7d ago
Jan 16th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-xodo-sign-e6139052
Brand impersonation: Quickbooks
8d ago
Jan 15th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-quickbooks-4fd791d1
Subject: Suspicious bracketed reference
11d ago
Jan 12th, 2026
Sublime Security
/feeds/core/detection-rules/subject-suspicious-bracketed-reference-663dbce4
Brand impersonation: SendGrid
11d ago
Jan 12th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-sendgrid-d800124f
Sendgrid onmicrosoft.com domain phishing
11d ago
Jan 12th, 2026
@ajpc500
/feeds/core/detection-rules/sendgrid-onmicrosoftcom-domain-phishing-271f4ae9
Attachment: HTML smuggling - QR Code with suspicious links
11d ago
Jan 12th, 2026
Sublime Security
/feeds/core/detection-rules/attachment-html-smuggling-qr-code-with-suspicious-links-010e757d
Callback phishing via DocuSign comment
11d ago
Jan 12th, 2026
Sublime Security
/feeds/core/detection-rules/callback-phishing-via-docusign-comment-48aec918
Russia return-path TLD (untrusted sender)
11d ago
Jan 12th, 2026
Sublime Security
/feeds/core/detection-rules/russia-return-path-tld-untrusted-sender-588b3954