What is blacklisting
A blacklist is a list containing all elements that are not automatically able to access a certain area. Within Leaseweb, when we speak about blacklists and blacklisting we refer to email blacklists. In practice, when you would use your blacklisted IP-address for email traffic, the email will either not get through to the recipient or will end in the recipient’s spam box.
Blacklisting means that the IP-address is listed on a blacklist.
IP-addresses may also be listed on greylists. A greylist contains elements that are temporarily blocked until an additional step is performed. In practice, IP-addresses used for email traffic are often ‘greylisted’ when no rDNS has been set up.
The opposite of a blacklist is a whitelist. In the case of whitelisting, all access is restrained apart from the elements listed on the whitelist.
Tips to avoid getting blacklisted
To avoid getting blacklisted, when sending emails for marketing purposes, always send them to mailing lists that contain email addresses obtained through double opt-in and with a valid unsubscribe URL, as single opt-in is not allowed according to most spam laws. For more information, please refer to our Spam policy
Additionally, creating additional DNS records decreases the chance of ending up on a blacklist. The following DNS records can help avoiding blacklists:
- DKIM record
Apart from getting blacklisted due to emailing behavior, your IP-address can also get listed due to a dirty range, open proxy, generic rDNS, infected servers being abused by a spam bot, or simply hosting a TOR exit node.
Are you blacklisted?
There are several online tools available to see whether your IP is blacklisted and if so, where it is listed.
The following two blacklist monitors check against all major and minor blacklists for a quick overview:
- www.mxtoolbox.com - If an IP address is listed, the listing will appear on top, in red. By clicking on it, the website for the blacklisting opens, and further instructions are provided there.
- www.blacklistalert.org - If an IP address is listed it will appear so in red. If applicable, an URL is made available to go to the blacklist.
How did I get blacklisted?
An IP address could be blacklisted for several reasons and on several occasions. If a report is provided and you do not act upon it, your IP address can be blocked access to a website, a country, part of the world, or from sending email.
How to remove my IP address from a blacklist?
For most blacklists, you can request delisting yourself by following a few simple steps. Below we explain which steps to take per provider.
If a block affects a range, the Compliance department will investigate the issue and will try to solve it. If it is an individual block, please contact the website that blocked your IP-address directly. Below an overview of the most common blacklists is provided, and where and how to delist them.
What to do
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- Secure your webserver
If you were blacklisted due to email accounts being compromised and used for sending out spam, please make sure the source of the problem is removed by securing your mail server and, if applicable, your websites.
- Ensure your IP-address is not listed on any blacklists
Use a tool such as MxToolbox (http://mxtoolbox.com/blacklists.aspx), a blacklist lookup tool that checks your server IP address against over 100 DNS based email blacklists, to verify that your IP address is not listed on any other blacklists. If this above step returns any listings, please follow the instruction on MxToolbox, or those explained in this page, in order to get the IP addresses de-listed.
- Set a SPF record
Microsoft blocks email from IP addresses that are not specified in the DNS zone file of the sender's domain. An SPF record is a TXT record that you can setup in your DNS zone file. The TXT record authorizes specific hosts to send email from a certain domain. To read more about TXT records, please visit our article on DNS record types.
- Set up a PTR record
Just like in case of missing SPF records, Microsoft generally does not accept emails from IP addresses that do not identify itself with a pointer record (PTR). You can set your PTR record in the Customer Portal. To read more about PTR records, please visit our article on PTR records and Reverse DNS.
- Verify your mail server setup
To verify whether you have completed the above steps successfully, use the MxToolbox diagnostics tool: http://mxtoolbox.com/diagnostic.aspx. If any of the checks fail, please follow the provided suggestions.
- Request delisting with Microsoft
If you succeeded with all above steps, you can proceed by requesting delisting through Microsoft’s sender information form.
Please note that the Compliance Department is unable to assist with requesting delisting for Microsoft products.
Never attempt to delist an IP address (or range) when you did not follow up on the cause of the blacklist. Make sure the reason for the blacklist is removed from the source, or the malicious activity has been ceased.
Every time a delisting is requested with the cause not removed, the delisting will get difficult each time you fail to comply.