Function choose_lane 

fn choose_lane(
    card: &Card,
    ctx: &Context<'_>,
    checks: &Checks,
    admission: &Admission,
    learned: Option<(&Filter, Verdict)>,
) -> (Lane, Reason)

The lanes are decided in this order: set aside; for a shielded address, hostile (both admission); what your own spam filter flagged or would move, as you chose (review); codes; projects; what you sent yourself; a shielded address’s own lane; addresses ranked below; newsletters and automatic senders; the screener; people you know.