Give mechapets.space an IPv6 address Ask your hosting provider for the site's IPv6 address (or the hostname to point at), then publish it as an AAAA record. If your host doesn't offer IPv6, a proxy that does can sit in front. How to add an AAAA record
www.mechapets.space is hosted on Vercel, which has no IPv6 It points at cname.vercel-dns.com, and that name has no AAAA record — so nothing you add in your own DNS can give it IPv6. Put an IPv6-capable proxy in front (Cloudflare's proxied DNS does this), or host somewhere that offers IPv6. Which platforms offer IPv6
Mail servers without IPv6 eforward1.registrar-servers.com, eforward2.registrar-servers.com, eforward3.registrar-servers.com, eforward4.registrar-servers.com, eforward5.registrar-servers.com have no AAAA record, so mail from IPv6-only servers can't reach them directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.
Visitors on IPv6-only networks (many mobile carriers) can still reach it, but only through a translator their carrier runs (NAT64). The site itself has no IPv6 address — and you can't make one up from the IPv4. Why some hosts don't offer it
Copy the evidence— a citation-ready record of this measurement