3 add the ReCAPTCHA to the landing page and email domain-based yandex in the Sender

On landing, which is on a VPS server, you will need to supply ReCAPTCHA 3.
The site is pure html and css
Requests go to spam, therefore you need to change the domain sending mail to @yandex.ru

The site is in the zone .Russia

All actions performed must describe in detail (what and how was done)