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Open Relay Check

What is Open Relay?

Open Relay is an SMTP server that allows relaying of email messages for any sender. In other words, its an MTA (Mail Transfer Agent) that will relay emails for any third party without any authentication.

Why does open relay have a negative effect?

Due to the feature that allows Open Relay servers to relay emails for anyone, spammers could use these servers to send out mass emails which consumes bandwidth, server usage and the possibility of the mail server being classified in a Black list. This could lead to financial losses for the business due to the resources used and possible disruptions of emails because of the mail servers being black listed.

How do i test if my Mail server allows Open Relay? Is there a list of mail servers that i can check with for this?

You can check to see if your mail server allows for open relay by using our Open Relay Check utility found on the home page. If you would like to see a list of mail servers that allow for third party relay, please visit www.ordb.org.

What if my mail server allows open relay?

It is highly recomended that necessary steps be taken to stop your mail server from allowing to relay for third party senders. Many mail servers reject emails from servers allowing for open relays and therefore this is detrimental to any business notwithstanding the costs associated if a spammer hijacks the machine.

Please click here to view our recommended solutions.

FAQ:Usage Policy: Contact:

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An Example Scan:

Scanning, please wait...

<< 220 mx2.mxshelter.com ESMTP Sendmail 8.13.4/8.13.4; Fri, 9 Sep 2005 11:04:39 -0400
>> HELO 192.168.2.227
<< 250 mx2.mxshelter.com Hello dnsgoodies.com [206.113.12.227], pleased to meet you
>> MAIL FROM:<spammer@192.168.2.227>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:<spammee@206.113.12.251>
<< 550 5.7.1 ... Relaying denied
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer@192.168.2.227>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:<"spammee@206.113.12.251">
<< 550 5.7.1 <"spammee@206.113.12.251">... Relaying denied
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer@192.168.2.227>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:spammee@206.113.12.251
<< 550 5.7.1 spammee@206.113.12.251... Relaying denied
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer>
<< 553 5.5.4 ... Domain name required for sender address spammer
>> RCPT TO:<spammee@206.113.12.251>
<< 503 5.0.0 Need MAIL before RCPT
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer@192.168.2.227>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:<spammee%206.113.12.251@dnsgoodies.com>
<< 550 5.7.1 ... Relaying denied
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer@192.168.2.227>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:<spammee@206.113.12.251@dnsgoodies.com>
<< 553 5.1.3 ... Invalid route address
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer@192.168.2.227>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:<206.113.12.251!spammee@dnsgoodies.com>
<< 550 5.7.1 <206.113.12.251!spammee@dnsgoodies.com>... Relaying denied
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer@192.168.2.227>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:<@dnsgoodies.com:spammee@206.113.12.251>
<< 550 5.7.1 <@dnsgoodies.com:spammee@206.113.12.251>... Relaying denied
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer@192.168.2.227>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:<206.113.12.251!spammee>
<< 550 5.7.1 <206.113.12.251!spammee>... Relaying denied
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<>
<< 250 2.1.0 <>... Sender ok
>> RCPT TO:<spammee@206.113.12.251>
<< 550 5.7.1 ... Relaying denied
>> RSET
<< 250 2.0.0 Reset state
>> MAIL FROM:<spammer@dnsgoodies.com>
<< 250 2.1.0 ... Sender ok
>> RCPT TO:<spammee@206.113.12.251>
<< 550 5.7.1 ... Relaying denied
>> RSET
Good News!
All tests for an open relay on your mail server failed.
Your mail server does not allow open relay.