[daijope ~]$ nslookup -q=mx aliyun.com 
Server:     10.125.250.210 
Address:    10.125.250.210#53 
 
 
Non-authoritative answer: 
aliyun.com  mail exchanger = 10 mx2.mail.aliyun.com. 
 
 
Authoritative answers can be found from: 
aliyun.com  nameserver = ns4.aliyun.com. 
aliyun.com  nameserver = ns5.aliyun.com. 
aliyun.com  nameserver = ns3.aliyun.com. 
mx2.mail.aliyun.com internet address = 110.75.48.150 
ns3.aliyun.com  internet address = 115.124.17.155 
ns4.aliyun.com  internet address = 110.75.20.27 
ns5.aliyun.com  internet address = 110.75.38.28 
 
 
[daijope ~]$ telnet 110.75.48.150 25 
Trying 110.75.48.150... 
Connected to 110.75.48.150. 
Escape character is '^]'. 
220 mx1.aliyun-inc.com MX AliMail Server(127.0.0.1) 
HELO taobao.com\r\n 
250 Ok 
MAIL FROM:<check@suho.com>\r\n 
250 Mail Ok 
RCPT TO:<zhoulai@aliyun.com>\r\n 
250 Rcpt Ok