type.inbound
and any(headers.hops,
any(.fields,
regex.icontains(.name, "X-Authenticated-Sender|X-Sender")
and regex.icontains(.value, "(anonymous|smtp)fox-")
)
or regex.icontains(sender.email.email, "(anonymous|smtp)fox-")
)
Playground
Test against your own EMLs or sample data.