The email adapter authorized senders entirely off the From: header, which is
attacker-controlled and unauthenticated by IMAP. An attacker could forge
From: an-allowlisted-address and pass both the adapter's EMAIL_ALLOWED_USERS
pre-filter and the gateway's allowlist authz (both key on the same spoofable
sender_addr), getting unauthorized commands executed by the agent.
Verify the From: domain against the trusted Authentication-Results header the
receiving mail server stamps (SPF/DKIM/DMARC) before trusting it for
authorization. Enforced only when an allowlist is in effect and allow-all is
off — fail-closed. Operators whose server does not stamp the header can opt
out via platforms.email.require_authenticated_sender: false (or
EMAIL_TRUST_FROM_HEADER=true).
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