mail.you.pt has one IP number , which is the same as for you.pt, but no corresponding reverse pointer. you.pt, acr.pt, avic.pt, pavin.net, amsom.net and at least 100 other hosts point to the same IP. you.pt use this as a mailserver. you.pt is a domain controlled by two nameservers at servidorpt.com. They are on the same IP network. Incoming mail for you.pt is handled by one mailserver at you.pt themselves. mail.you.pt is hosted on a server in Portugal.