Link: Free file hosting with undisclosed recipients

type.inbound
// no previous threads
and length(body.previous_threads) == 0

// few links
and 0 < length(body.current_thread.links) < 10

// undisclosed recipients or all recipients cc'd
and (
  any(recipients.to, strings.ilike(.display_name, "undisclosed?recipients"))
  or (length(recipients.cc) > 0 and length(recipients.to) == 0)
  or (length(recipients.bcc) > 0 and length(recipients.to) == 0)
  or (
    length(recipients.to) == 1
    and length(recipients.cc) == 0
    and length(recipients.bcc) == 0
    and all(recipients.to, .email.email == sender.email.email)
    and all(recipients.to, .email.email != mailbox.email.email)
  )
)

// links to free file hosts or free subdomain hosts
and any(body.current_thread.links,
        (
          .href_url.domain.root_domain in $free_file_hosts
          or .href_url.domain.root_domain in $free_subdomain_hosts
        )
        and .href_url.domain.subdomain is not null
        and .visible
        and not (
          .href_url.domain.root_domain == "googleusercontent.com"
          and strings.istarts_with(.href_url.path, "/mail-sig")
        )
)

// negate listmailers & benign threads
and not (
  any(headers.hops, any(.fields, .name == "List-Unsubscribe"))
  or any(ml.nlu_classifier(body.current_thread.text).intents,
         .name == "benign" and .confidence == "high"
  )
)

// unsolicited and passing auth, or failing/missing dmarc
and (
  (
    coalesce(headers.auth_summary.dmarc.pass, false)
    and not profile.by_sender().solicited
  )
  or (not coalesce(headers.auth_summary.dmarc.pass, false))
)