Syntax is OK
2 Email address domain exists.
3 Email address domain has mail server(s).
MX records:
preference exchange
10 mx3.qq.com
20 mx2.qq.com
30 mx1.qq.com
4 SMTP session timed out.
SMTP session:
[Contacting mx3.qq.com...]
[Connected]
[Timed out]
[Contacting mx2.qq.com...]
[Connected]
[Timed out]
[Contacting mx1.qq.com...]
[Connected]
[Timed out]