Handy SMTP Handshake for testing with Telnet

Published on Wednesday, February 8, 2017

Hi,

It's always useful to test SMTP service, using Telnet, so these are the commands needed:

First of all, connect through Command Prompt or Powershell

Telnet x.x.x.x tcpPort

For Example Telnet 10.0.2.1 25

You will get a welcome message from SMTP Server, like this one:

220 exc02.contoso.com Microsoft ESMTP MAIL Service ready at Wed

then write sequentially hitting enter at each line what is coloured in green here (no color lines are server responses)

EHLO mailtesting
AUTH LOGIN
334 VXNlcm5hbWU6
Y29udG9zb1xhY2NvdW50
334 UGFzc3dvcmQ6
dGhlUGFzc3dvcmQ=
MAIL FROM:
RCPT TO:
DATA
Subject: here comes the test 
This is the email content.
.
250 Queued mail for delivery 

Important notes: You have to hit enter twice after subject input. account name and password are entered Base64 encoded, so first encode that information using for example this site.

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