]
] 24) Again, how will you stop spammers from forging this
] domain?
] Nothing can stop a spammer from forging a .mail
] domain, but the entire TLD DNS system - the thing that
] controls all domains under this TLD - is run by the
] Sponsor Organization. What this means is that a system
] that tests to see if the connecting .mail domain is a
] valid, "no spam" domain, will be able to spot an attempt
] to forge it right at the start of the SMTP transaction.
] Attempts to forge can be rejected on the spot, or passed
] on to further spam-filter checks.

They need to publish a RFC-level document detailing how this
would work. I think they're saying a mail from amazon.com
would have an envelope sender of mx23.amazon.com.mail. The
receiving MTA can then check that the connecting host really
is mx23.amazon.com and if so, let the mail through.

Spamhaus .mail TLD - Frequently Asked Questions (FAQ)