How to: test the functionality of an outgoing mailserver

stoneis · #1 05-29-2012, 06:20 AM

You have just setup an SMTP server and want to test it (or you want to test an existing server). Then we have a little guide for you:

The full post can be found here.

1 Requirements

Installation of Telnet on Windows 7

Press the following keys at the same time: Windows + R
and fill in the following, followed by :

Code:

pkgmgr /iu:"TelnetClient"

Installation of Perl

Go to http://strawberryperl.com/ and install the appriopriate version.

2. Connecting with the outgoing mailserver

Opening the connection

Press the following keys at the same time: Windows + R
and fill in the following, followed by: cmd

In the opened black screen enter: telnet hostname 25
(alternatively this can be 587 if configured and your ISP does block port 25)

After a succesful connection you receive:

Code:

220 ESMTP

Listing the functionality

Enter:

Code:

EHLO testing.com

The out should be like:

Code:

250-servername

Name of the server

Code:

250-PIPELINING

Multiple commands can be entered at the same time

Code:

250-SIZE 10240000

The maximum message size is 10,000KB

Code:

 250-VRFY

It is possible to verify existance of mailaddresses

Code:

 250-ETRN

Allowed to queue mail

Code:

 250-STARTTLS

TLS encryption is supported

Code:

 250-AUTH PLAIN LOGIN DIGEST-MD5 CRAM-MD5

All of the authentication methods

Code:

 250-ENHANCEDSTATUSCODES

Just as the label reads

Code:

 250-8BITMIME

8 bit data transmission

Code:

 250 DSN

Delivery Status Notification

Crafting the authenticationstring

Press the following keys at the same time: Windows + R
and fill in the following, followed by : cmd
Navigate to the folder where you installed Strawberry Perl.
eg. cd C:\strawberry

In the following command replace john with your mailname (eg. info), example.com with your domainname (eg yourdomain.com) and changeme by your password.

Code:

perl -MMIME::Base64 -e "print encode_base64 (\"\000john\@example.com\000changeme\")"

Special charachters in mailname, domainname or password, are to be preceded by a \
eg ch@ng3m3 has to be noted as ch\@ng3m3
more info on the escape charachter can be found on http://en.wikipedia.org/wiki/Escape_character

The output will be something like:

Code:

AGpvaG5AZXhhbXBsZS5jb20AY2hhbmdlbWU=

Authenticating to the outgoing mailserver

Enter AUTH PLAIN followed by the code we received earlier:

Code:

AUTH PLAIN AGpvaG5AZXhhbXBsZS5jb20AY2hhbmdlbWU=

The expected response is:

Code:

235 go ahead

Providing the sender and recipient references

Sender:

Code:

MAIL FROM: <john@example.com>

Recipient:

Code:

RCPT TO: <test@otherdomain.com>

Providing the data

Enter following commands:

Code:

 
DATA
 
From: John 
To: Nobody 
Subject: test
test
.

Note: test is followed by a dot, this is important
After this dot, you need to press <enter> twice.
You will now receive a reply that the mail has been queued correctly, and you will receive the queue ID.

Code: