Telnet

Telnet can be used to check open ports on a server, on the other hand, Telnet can also be used to test sending emails.

How Telnet Works

Telnet works by accessing the destination server via a port.

Implementation

Check Open Port

$ telnet regiapriandi.com 25
Trying 103.186.65.63...
Connected to regiapriandi.com.
Escape character is '^]'.
220-mail.regiapriandi.com ESMTP Postfix

Send Mail

root@mail:~# telnet regiapriandi.com 25
Trying 103.186.65.63...
Connected to regiapriandi.com.
Escape character is '^]'.
220 mail.regiapriandi.com ESMTP Postfix
HELO regiapriandi.com
250 mail.regiapriandi.com
MAIL FROM: regi@regiapriandi.com
250 2.1.0 Ok
RCPT TO: regiapriandi012@gmail.com
250 2.1.5 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
Hello
.
250 2.0.0 Ok: queued as 4SB8bn049Hz1wVT
quit
221 2.0.0 Bye
Connection closed by foreign host.