mx.google.com gave this error: Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication

I have faced an issue for one of my client. Their emails are found as rejected by google and gave the NDR as follows mx.google.com┬árejected your message to the following email addresses: name@gmail.com (name@gmail.com) Your message wasn’t delivered due to a permission or security issue. It may have been rejected by a moderator, the address … Continue reading “mx.google.com gave this error: Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication”