pub fn organisational(domain: &str) -> Option<String>Expand description
A domain’s organisational domain, as DMARC’s relaxed alignment reads it
(RFC 7489 §3.2): the name registered under its public suffix, by the
Public Suffix List (“mail.example.co.uk” → “example.co.uk”; the psl
crate carries the list). None for a public suffix itself (“co.uk”,
“github.io”), which nobody owns as a whole.