ACNSpam Blacklist Removal

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How to remove your domain from Spam Blacklists

Often the first time you know you have a problem is when you try to send a legitimate email and you get a bounce back message containing a line similar to one of the below:

#5.7.1 smtp;550 5.7.1 Rejected:  

421 4.7.1 Service unavailable; Client host [123.456.789.101] blocked  

Host [123.456.789.101] said: 554 Denied [CS] [] (Mode:normal) (in reply to end of DATA command)  
Our system has detected an unusual rate of     550-5.7.1 unsolicited mail originating from your IP address. To protect our     550-5.7.1 users from spam, mail sent from your IP address has been blocked. #550 OU-001 (BAY0-MC3-F23) Unfortunately, messages from 123.456.789.101 weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to  

To check if you have been blacklisted on any sites for sure, there are two great websites. Here is how to use them:  

First off you need to find out the IP address of the site you have been sending mail out from, this is usually contained in the bounce back message you received, but if you don’t have that:
Go to and enter your domain name (the bit after the @ in your email address), then click the “MX Lookup” button. The result will look something like below, I looked up as an example

mx lookup

You will see in this example had four MX Records, you may only have one or two. Each record will have its own unique IP Address. If you always use the same network such as your office workplace, then you can check what IP Address you are using by going to (this doesn’t always mean that is the IP your email sends from).

It won’t harm to check more than one IP Address if you are not sure which is yours.   The first site to check your IP Address with is
Enter your IP and click the “Blacklist Check” button, it will then work away and check many Spam lists across the internet. If you are listed on any, you can simply Google the list and find instructions on their site to remove your IP. Note: Check the reason they blocked you first, if it was because you were sending out Spam (unsolicited email) be sure you have removed any Viruses before removing yourself from any lists, it is also worth making sure you are not a relay by clicking the “SMTP Test” link on the above “MX Lookup” button.
The tool at the MXToolbox website is a combined check across many of the popular Spam Blacklist databases.

The second blacklist site we use to lookup is This site includes many Blacklists that are not checked by, as before always deal with the reason they blocked you BEFORE removing your IP from their sites, otherwise it may be harder to get you off their databases next time!