mail.nmobile.vn has one IP number , which is the same as for nmobile.vn, but no corresponding reverse pointer. hssv.vn, itus.vn, apcs.vn, vgac.net, 19st.net and at least 87 other hosts point to the same IP. nmobile.vn use this as a mailserver. nmobile.vn is a domain controlled by three nameservers. All of them are on different IP networks. Incoming mail for nmobile.vn is handled by one mailserver at nmobile.vn themselves. mail.nmobile.vn is hosted on a server in Vietnam.