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
Credential phishing: Financial lure via ActiveCampaign infrastructure
3d ago
Mar 27th, 2026
Sublime Security
Callback phishing via Microsoft comment
4d ago
Mar 26th, 2026
Sublime Security
Brand impersonation: Robinhood
4d ago
Mar 26th, 2026
Sublime Security
Cloud storage impersonation with credential theft indicators
7d ago
Mar 23rd, 2026
Sublime Security
Credential phishing: Suspicious subject with urgent financial request and link
7d ago
Mar 23rd, 2026
Sublime Security
Spam: Fake dating profile notification
10d ago
Mar 20th, 2026
Sublime Security
Brand impersonation: Meta and subsidiaries
10d ago
Mar 20th, 2026
Sublime Security
Link: Free file hosting with undisclosed recipients
11d ago
Mar 19th, 2026
Sublime Security
Brand impersonation: DocSend
12d ago
Mar 18th, 2026
Sublime Security
Service abuse: Domains By Proxy sender
12d ago
Mar 18th, 2026
Sublime Security
EML attachment with credential theft language (unknown sender)
13d ago
Mar 17th, 2026
Sublime Security
Brand impersonation: Wix
14d ago
Mar 16th, 2026
Sublime Security
Brand impersonation: FedEx
14d ago
Mar 16th, 2026
Sublime Security
VIP impersonation with w2 request with reply-to mismatch
18d ago
Mar 12th, 2026
Sublime Security
Service abuse: Google Firebase sender address with suspicious content
18d ago
Mar 12th, 2026
Sublime Security
Brand impersonation: Booking.com
18d ago
Mar 12th, 2026
Sublime Security
Brand impersonation: SendGrid
18d ago
Mar 12th, 2026
Sublime Security
BEC/Fraud: Reply-chain manipulation with urgent keywords and self-reply
19d ago
Mar 11th, 2026
Sublime Security
Brand impersonation: McAfee
19d ago
Mar 11th, 2026
Sublime Security
Impersonation: Legal firm with copyright infringement notice
20d ago
Mar 10th, 2026
Sublime Security