Use Telnet to log in to the SMTP service to send mail

Recently in the company's anti-spam system, found that there is a mail system sent a lot of spam, use Telnet login up, try to send a message, unexpectedly can successfully sent, originally this post office system is no limit, was used, alas, here is how to use the command telnet To make a forged hand-sent message.

# telnet MAIL.CORATUR.CU 25

Helo coratur.cu

Mail from:<[email protected]>

RCPT to:<[email protected]>

Data

From:[email protected]

To:[email protected]

Subject:test Mail

This is Test mail!

. Notice there's a point here, the meaning of the end;

Status Code Description:
220: Service Ready
250: Request mail action is correct, complete (helo,mail from,rcpt to,quit instruction execution succeeds return this information)
235: Certification passed
221: Processing
354: Start sending data, end with. (This information is returned when the data instruction executes successfully)
500: syntax error, command not recognized
550: The command cannot be executed, the mailbox is invalid
552: Interrupt Processing: User exceeds file space

This article is from the "Square Hill" blog, please be sure to keep this source http://63638790.blog.51cto.com/513514/1549326

Use Telnet to log in to the SMTP service to send mail