Here is what they tell from the Host:
It certainly looks like there is an issue with the DNS zone configuration.
Here's an example transcript from an MX record lookup attempt on domain.email:
1 demand.alpha.aridns.net.au XX.XXX.XXX.X NON-AUTH 46 ms Received 2 Referrals , rcode=NO_ERROR domain.email. 86400 IN NS ns1.box.domain.email,domain.email. 86400 IN NS ns2.box.domain.email,
2 ns2.box.domain.email XXX.XXX.XX.XXX TIMED-OUT 500 ms , rcode=NO_DATA
2 ns1.box.domain.email XXX.XXX.XX.XXX TIMED-OUT 0 ms Loop Prevented, rcode=NO_DATA
And here is what they tell from namecheap
As we checked, it appears that the private Nameservers are not configured correctly.
According to the Verisign Nameservers checker, they are not registered:
No match for nameserver "NS1.BOX.DOMAIN.EMAIL".
No match for nameserver "NS2.BOX.DOMAIN.EMAIL".
Last update of whois database: Fri, 17 Mar 2017 00:16:58 GMT
To check the possible issue from our side, we have double-checked the setup and can confirm that the Glue records are set in your Namecheap account.
Thus, it must mean that there are no corresponding A records for the "ns1.box" and "ns2.box" are either not created or not working properly.
Thus, we would suggest to contact your Hosting service vendor to double-check and confirm that the A records are created and working properly.
I cannot touch the A records on MiaB, so does anybody have any idea if I have any options to make this work.