Works, although it does feel a little incoherent setup wise it  sometimes required and not required, and having access to reverse dns means i can mail google in ipv6, your experience might be different (not here) than the zoo’s
Don’t forget about spf records
Being ipv6 is very mostly silicon valley based (not amazon) i was surprised that some try and abuse ipv6 and the domain name system
Domain unknown senders
Although we do see them trying this from ipv4 too
No damage was done and the ipv6 and ipv4 protocol matched the fake domain.
Ipv6 accounts for 25% of dns traffic and not many ipv6 mx entries so 1% of email traffic unless you email gmail all the time.