Telnet SMTP send mail timeout - email

Question

I want to use telnet to send an e-mail with SMTP. It seemed that I had connect to the mail service successfully. And the message had been put in the queue too. But why did the SMTP service failed to send the message to the received address?
When I searched the solution by the internet, someone had said that firewall should paid it. But I have no idea about the relationship between the firewall or antivirus software and telnet.
This is my command:
220 smtp-5-124.smtpsmail.fmail.xd.sinanode.com ESMTP
helo a
250 smtp-5-124.smtpsmail.fmail.xd.sinanode.com
auth login
334 VXNlcd5hbWU6
a25vd215aGV2341241fasYS5jbg==
334 UGFzczdvcmQ6
UmF5V2adfa23adsfZzgyNA==
235 OK Authenticated
mail from: <knowmyheart#sina.cn>
502 unimplemented (#5.5.1)
mail from:<knowmyheart#sina.cn>
553 Envolope sender mismatch with login user..
mail from:<knowmyheart#sina.cn>
250 ok
rcpt to:<517447201#qq.com>
250 ok
data
354 End data with <CR><LF>.<CR><LF>
subject: test
to:<517447201#qq.com>
from:<knowmyheart#sina.cn>
Testttttttttttttt!
.
250 ok queue id 6744281442287
451 Timeout.
By the way, I tried it both on Windows 10 and Ubuntu-15.10. And both of them failed with the same question.

Answer 1

Finally, I found where I was wrong.
In my previous case,I failed to send a e-mail with the above code.I had succeeded in connecting with the SMTP server, and everything worked except the "Timeout" response. Actually, the "Timeout" didn't mean I failed to send a e-mail but lose the TCP connection. Hours Later, I login my e-mail, which was used for sending, finding that I receive a mail. The mail told me the e-mail I sent hours before with telnet was given back, failing to post. So it meant that the reason was hardly because of my telnet client, but in server or something else.
Finally, I found that it was because of my mail format. In my previous code, after I sending keyword -- "data", I immediately send the content.
data
354 End data with <CR><LF>.<CR><LF>
subject: test
to:<517447201#qq.com>
from:<knowmyheart#sina.cn>
Testttttttttttttt!
.
250 ok queue id 6744281442287
When I changed it to this, it worked.
data
354 End data with <CR><LF>.<CR><LF>
subject: test
to:<517447201#qq.com>
from:<knowmyheart#sina.cn>
Testttttttttttttt!
.
250 ok queue id 6744281442287
Notice that the difference between the codes is the empty line before the content in this mail. "subject", "to" and "from" are the headers. Between the header and the content, there must be an empty line.
Similarly, the headers in mail can be ignored. The code is like this:
data
354 End data with <CR><LF>.<CR><LF>
Testttttttttttttt!
.
250 ok queue id 6744281442287
451 Timeout.
Even if there is a "Timeout", it affect nothing but break the tcp connection between localhost and smtp server.