Lethe's DNSBL

There are currently 5225079 entries.

Welcome. This is my personal blacklist, but it has evolved into something bigger, which a few ISPs now use. The TL;DR point of this blacklist is to block spammers hosted on spam haven providers that are totally irresponsible and help pollute the internet. Most of them know who they are. No IP listed here has been listed for more than 6 months, and every IP has sent at least 2 spammy messages within a month period. This is considered a very non-aggressive blacklist.

Update April 9th 2016: Now with IPv6 support!

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Are you an ISP or hosting provider?
If you are an ISP or web host provider and wish to use this blacklist, access can be provided to direct delisting. Contact Us for more information.

Top Spam ISPs
 The current list of blacklisted hosts, due to trap hit being above 60% and no replies from their abuse; thus completely irresponsible hosts that harbour spammers due to easy money:
Enzu Inc (AKA ScalableDNS). More here.
Nobis Technology Group. More here.
Global Frag Networks. They simply ignore abuse complains.
ExactTarget, Inc.. They ignore spam complaints and provide invalid unsubscribe links.
Psychz Networks. More here. They are a spam haven that take no action against spammers.
CloudFlare. They are a spammer haven and refuse to remove spam from their network. They are a completely irresponsible host that willfully allow malware and spam through their network for profit. More info here
SharkNet. Our newest spammer haven entry. More here.
CHINANET-ZJ-HU. Major spam haven; ignores abuse complains.
* Note that these will never expire. The host has to contact us and prove they no longer willingly host spammers for profit.

 I've been running a mail server for longer than I care to remember. The more time passes, the more irresponsible ISPs show up left and right to help spammers. Blocking those spammers has become increasingly difficult, especially for the non-tech savvy people, or those too busy to deal with it. This is my solution. Feel free to use it.

How does it flag spam?
 The methodology used here is very simple: spam traps. Once an email is sent to the trap, the unsubscribe linked is accessed automatically, and the IP flagged. If the same IP sends spam again within 30 days, a spam report is forwarded to their hosting provider and/or domain host. If, again within 30 days, more spam is received from the IP, it's added to the blacklist. If there is no unsubscribe link, this step is skipped since it's an extra confirmation of spammers.

Can I search the blacklist
 Yes, enter the IP address in the box below, and press search.

Alternatively, you can use my multi-lookup tool, which includes this DNSBL.

Can I test IPs against the blacklist
 Yes. Do a DNS check with a reverse IP. Here are some examples:
In the above examples, the real IP addresses would be and respectively. Any "not found" message means the IP you checked is not listed. If you are unsure, use this web interface.

How do I use the blacklist
- cPanel
- Exim
- DirectAdmin
- Plesk
- Postfix
- Qmail
- Sendmail
- MS Exchange
Use "dnsbl.lethe.ca" as name/url.

What are the 127.0.0.x results?
 127.0.0.x, or x.0.0.127.dnsbl.lethe.ca are the reasons why you were blocked. For a complete description, see,,,, and error pages.

Help, I'm listed. How do I get removed?
 First, find out why you are listed. Unlike some blacklist, we know how the real world works. You might not be a spammer, and you're still listed. Are you running Wordpress or Joomla or other CMS with some sort of exploit sending out emails? Did you just get that new IP and it's blacklisted? Whatever the reason, you'll have to get in touch with us, and explain; unless the listing is older than 6 months old without new hits to the traps, in which case it'll be deleted automatically.

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