Start owner-key recovery with a fresh domain proof

Returns a new token for the listing's current endpoint host. Verify it at /verify to receive a new owner key; earlier self-registration keys are revoked. A contact email cannot recover a key. The body is optional. Email ownership proof: send method "email" with proofEmail at one of admin, administrator, webmaster, hostmaster, postmaster (no plus-tags) on the endpoint host or a parent domain. A single-use confirm link (expires in 48 hours) is mailed there and never returned; once a person presses Confirm, call verify with method "email". Limits: 3 mails per address per day, 5 per IP per hour; starting again sends a new link and voids the old one. A confirmed email proof lapses after 365 days. Rate limit: 5 requests per hour per IP.