• Sublime Core Feed
Medium Severity

Reconnaissance: Empty subject with mismatched reply-to from new sender

Description

Message with no subject line from a new sender where the reply-to address differs from the sender address, potentially indicating header manipulation or impersonation tactics.

References

No references.

Sublime Security
Created Feb 6th, 2026 • Last updated Feb 6th, 2026
Source
type.inbound
and profile.by_sender_email().prevalence == "new"
and subject.base == ""
and length(headers.reply_to) > 0
and sender.email.email not in map(headers.reply_to, .email.email)
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