Просто так...вдруг не все баш почитывают изредка.

Код:
waso@localhost ~ $ nslookup -q=mx microsoft.com
Server:         aaa.bbb.ccc.ddd
Address:        ddd.ddd.ddd.ddd#53

Non-authoritative answer:
microsoft.com   mail exchanger = 10 mail.global.frontbridge.com.

Authoritative answers can be found from:
microsoft.com   nameserver = ns4.msft.net.
microsoft.com   nameserver = ns5.msft.net.
microsoft.com   nameserver = ns1.msft.net.
microsoft.com   nameserver = ns2.msft.net.
microsoft.com   nameserver = ns3.msft.net.

waso@localhost ~ $ telnet mail.global.frontbridge.com 25
Trying 216.32.181.22...
Connected to mail.global.frontbridge.com.
Escape character is '^]'.
220 mail161-wa4.bigfish.com ESMTP Postfix EGGS and Butter
                                  ^^^^^^^
quit
221 Bye
Connection closed by foreign host.
Забавно...где же эксченж сервер?