I'm a unix admin. The idea that anything a mail server connects to holds any importance is hilarious on its face. By default mail servers talk to other mail servers all over the world daily. Its like saying because a person from Russia called the land line at a business(that they advertise on their web page, phone book etc) and talked to someone for 5 min that the business definitely is a Russian mob front for laundering money. Its just silly and a huge assumption that makes zero sense.