• Sublime Core Feed
Medium Severity

Service abuse: Free provider with SendGrid routing

Description

Message From header includes a free email provider domain but is routed through SendGrid infrastructure, indicating potential service abuse for delivery evasion.

References

No references.

Sublime Security
Created Jan 8th, 2026 • Last updated Jan 8th, 2026
Source
type.inbound
and sender.email.domain.domain in $free_email_providers
and any(headers.domains, .root_domain == "sendgrid.net")
and not any(ml.nlu_classifier(body.current_thread.text).intents,
            .name == "benign"
)
and not any(ml.nlu_classifier(body.current_thread.text).topics,
            .name == "Bounce Back and Delivery Failure Notifications"
)
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