SMTP mail (impersonate the email server to contact the QQ server and send an email without a password)

Jixiuf @ JF ~ $ Telnet mx0.qq.com 25

Trying 58.251.149.190...
Connected to mx0.qq.com.

Escape Character is '^]'.
EHLO 10.2.0.2
8
(My IP)
220 ********************************
250 newmx33.qq.com
Mail from: <jixiuf@gmail.com>

250 OK
Rcpt to: <jixiuf@qq.com>

250 OK
Data

354 end data with <CR> <LF>. <CR> <LF>
From: jixiuf@gmail.combutasaserversoicansendmailwithoutpasswdandusername
Subject: maochongserversendmail

Test !!!
.

250 OK: queued
Quit

221 bye
Connection closed by foreign host.

==========================================================

Jixiuf @ JF ~ $ NSLookup

> Set type = mx
(Set the query type to MX, that is, Mail)
> QQ.com
(Query the internal email server of QQ.com)
Server: 127.0.0.1
Address: 127.0.0.1 #53

Non-Authoritative Answer:
QQ.com mail exchanger = 10 mx0.qq.com.

Authoritative answers can be found from:
QQ.com nameserver = dns1.imok.net.
QQ.com nameserver = dns2.imok.net.
QQ.com nameserver = dns3.imok.net.

// This is the query result (that is, the top telnet address. Note that the address here is not smtp.qq.com published on the QQ official website. The address requires a password and a user name, the following email server is not required)

Mx0.qq.com Internet address = 58.251.149.190
Mx0.qq.com Internet address = 58.251.149.191
Mx0.qq.com Internet address = 58.251.149.192
Mx0.qq.com Internet address = 58.251.149.193
Mx0.qq.com Internet address = 58.251.149.194
Mx0.qq.com Internet address = 58.251.149.195
Mx0.qq.com Internet address = 58.251.149.196
Mx0.qq.com Internet address = 58.251.149.197
Mx0.qq.com Internet address = 58.251.149.187
Mx0.qq.com Internet address = 58.251.149.188
Mx0.qq.com Internet address = 58.251.149.189

Dns2.imok.net Internet address = 61.152.100.5
Dns3.imok.net Internet address = 218.30.72.181
Dns1.imok.net Internet address = 219.133.40.202
>