Apex domains cannot have CNAME records.
Question and response
Question
dig mail2world.com. NS
Answer
mail2world.com. 1 NS ns10.mail2world.com.
mail2world.com. 1 NS dns.mail2world.com.
Authority
The response has no authority records.
Additional
dns.mail2world.com. 1 A 209.67.129.15
ns10.mail2world.com. 1 A 74.202.142.162
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0