eMail Open Relay Tester

The Relay tester allows easy sending of test messages to detect open relays.

Warning: this is no end-user-toy-tool

This tool is more or less for the 'system admin' who knows what he is doing. As a private internet user you almost never should have the need to 'relay test' anything. Some people might be annoyed if you test them...

Mail Relay

A mail relay is a host that accepts mail and forwards this mail to the receivers mailbox. This is done by passing it to other mail relays or (if known) put it into the receivers mailbox. So every internet provider and every user needs these relays if they want to send mail.

A well configured mail relay will only process mail from servers/users that are allowed to deliver or accept mail. As a rough idea take: mail for and from users in his domain. But some relays are configured as 'backup', others can be set up to process mails for multiple hosts. So sometimes the first look might be missleading.

Open Mail Relay

An open mail relay accepts *any* mail and tries to forward it to everywhere. This server is a good place to dump your 100.000.000 spam mails, hide yourself behind the server and let it do the evil part of the work.

The Test

After entering the needed data the test can be started. If the host accepts connections the mail processing starts. The open relay tester creates several mails, each with special from and to envelope headers. Every message gets a special subject to identify the tested pattern.

If the mail server accepts the mail it is still unsure that it is an open relay. So you have to wait until you receive your testmails back. Due to that it is *REALLY* important to use a working address in "Send Mail To:". And keep in mind that if the server is really an open relay *your* mail server might drop mails/connections from this server (and you won't see any answers).

Needed Data

Host to test	The host and the port you expect the mail server to run on.
Mail send FROM:	Will be used for the test envelope to generate the answer for the MAIL query.
Send Mail to:	Will be used for the test envelope to generate the answer for the Rcpt query. See comment above.
Helo name:	This is the identification you will send during connect.

The Report

Test for mail relay began at 27.02.2004 10:48:04	Time stamp
ID for test is LZKXFKIOHBJSMMFRPAPP	This ID helps to identify the test.
Host: secret	The data used for the test.
Port: 25
From: xxxxxx@xxxxxxxxxx
To: xxxxxxxx@xxxxxxxxx
Test YZLJWPNOWWHZTDKDVKZN-0	Sequenz of tests, an upcounting test ID and the to/from combinations.
To: <"xxxxxxx@xxxxxxxxx">
From: <xxxxxxx@xxxxxxxx>
Subject: YZLJWPNOWWHZTDKDVKZN-0
....

Use the disk icon to save the report.

The Protocol

It shows the handshake.