Hi, I tried several domains from the domain list provided by API, and all of them were unable to receive emails. I tried to send an email to them from my email address and got this error:
Reporting-MTA: dns; forward500p.mail.yandex.net
X-Yandex-Sender: rfc822; [MY EMAIL HERE]
Arrival-Date: Thu, 30 Sep 2021 00:44:45 +0300 (MSK)
Final-Recipient: rfc822; email@example.com
Remote-MTA: dns; mail.mailkept.com
Diagnostic-Code: SMTP; 550 I cannot deliver mail for firstname.lastname@example.org
Waiting for your answer, thank you.