Some SMTP Banner test tool returns root DNS information, why? How to prevent this?

[lexcomputer]

I tried https://tools.verifyemailaddress.io/ by using email [email protected]. It returned root DNS server.
Anyway, other test tool likes mxtoolbox.com returns mail server hostname as specified in MX record.

How can I force https://tools.verifyemailaddress.io/ so that it will return server hostname as in MX record?

My MX record is
mail A xxx.xxx.xxx.xxx
officework.co.th MX 10 mail

Thank you.

 

[Richard G]

Change:

officework.co.th MX 10 mail

to

officework.co.th. MX 10 mail

mind the trailing dot on the hostname!! If that is not present, the record will not work.
That is the reason that your mx is still pointing to mrit4you instead of your domain name.