#Adding Namecheap glue and nameserver records for a mailinabox server
First you need to create the "glue records" by adding a new "Personal DNS Server" in the "Advanced DNS" tab of your domain. Add both the "ns1.box" and "ns2.box" nameservers. (See here for more information.)
You can view your added nameservers by using the search feature and specifying "ns1.box" or "ns2.box" nameservers:
Now all you need to due to add these personal nameservers as nameservers for your domain: