Connecting to smtp.gmail.com via command line

user_163373 0
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I am in the process of writing an application that sends mail via an valid GMail user ID and password.

I just wanted to simulate the SMTP connection on my Windows XP command line, and when I telnet smtp.gmail.com at 465 port - I don't see any thing. A blank command window with title Telnet smtp.gmail.com opens with cursor. When I type in EHLO or usual SMTP handshake commands, the prompt just closes.

I am unable to figure out whats going wrong and where. I tried connecting to 587, it does not connect in telnet at all. Could anyone please clarify if I am doing something wrong?

telnet smtp gmail
10 Answers

Start session from terminal:

openssl s_client -connect smtp.gmail.com:25 -starttls smtp

The last line of the response should be "250 SMTPUTF8"

Initiate login

auth login

This should return "334 VXNlcm5hbWU6".

Type username

Type your username in base64 encoding (eg. echo -n 'your-username' | base64)

This should return "334 UGFzc3dvcmQ6"

Type password

Type your password in base64 encoding (eg. echo -n 'your-password' | base64)

Success

You should see "235 2.7.0 Accepted" and you're are successfully logged in

user_4349800

How to connect to "Google SMTP mail server" from the command line?

1] SSL connect command

openssl s_client -connect {{server_name}}:{{server_port}} -crlf -quiet -starttls smtp

with variables

  • server_name: smtp.gmail.com
  • server_port: 587
  • user_name__hash: echo -n '{{user_name}}' | base64
  • user_password__hash: echo -n '{{user_password}}' | base64

2] SMTP mail server commands - every command in one line

auth login
{{user_name__hash}}
{{user_password__hash}}
helo {{server_name}}
mail from: <{{message_from}}>
rcpt to: <{{message_to}}>
DATA
from: <{{message_from}}>
to: <{{message_to}}>
subject:{{message_subject}}
Content-Type: text/html; charset='UTF-8'; Content-Transfer-Encoding: base64;
MIME-Version: 1.0
{{message_content}}
.
quit
user_13476010
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