Bizarro - Acabei de testar o teste smtp no link para você e recebi uma resposta clara.
Connection Test I was able to connect on port 25 to mail.smoothstoneservices.com
HostName in Greeting The hostname in the greeting message is
mail.smoothstoneservices.com
Accepts Null <> Sender The SMTP server is accepting NULL <> Sender
Accepts Mail to Postmaster The SMTP server is accepting mails to [email protected]. This is a good thing, as this addres is used to send out system communications
Accepts Mail to Abuse The SMTP server is accepting mails to [email protected]. This is a good thing, as this address is used to send out abuse communications
Accepts Mail to domain literals The SMTP server is accepting mails to postmaster@[IP_ADDRESS]. This is a good thing, as this address is used by people that don't know your domain name!
Is Open Relay I have tried to send out email through the SMTP server and i wasn't able. This is a good thing, as it seems that your server isn't an open relay.
Também acabei de telnetar para a porta 25 em 69.164.221.183 e consegui 220 mail.smoothstoneservices.com
Gostaria de saber se algo estava errado anteriormente e agora você está recebendo um resultado em cache quando verificar.
Edit: Ainda mais estranho - Acabei de verificar o www.dnsqueries.com com uma configuração de teste em que o registro A não corresponde ao nome do host especificado na saudação SMTP, e ficou feliz com isso.