3 ms·

I believe SMTP attempts delivery to the A record if there is no MX record.

• Xylakant 10y ago
  Indeed, if no MX record is known, but an A record is, mail will be sent to that host. However, example.(com,org) are designated testing domains by RFC and any self-respecting mail server should know not to forward mails there. And on top of that, since the domains are designated testing domains, they do not accept mails.
  • jakobdabo 10y ago
    The right thing to do in this situation is to use RFC 7505[1] (Null MX Records). [1] https://2rfc.net/7505 https://2rfc.net/7505
    • Xylakant 10y ago
      Cool, didn't know that. Thanks for teaching me something today.
    • deleted 10y ago
      [deleted]