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The SMTP IPv4 DNS Block List


Acceptable use policy
(List usage/abuse/misuse:)
Updated: August 24, 2017

POLICY: These lists are designed for email server use only. Any other use is prohibited any does not comply with our acceptable use policy. As in "commercial use" (which includes any of our lists results in any product or service which is then sold or resold) does not comply with our acceptable use policy. It is not intended for use to block any IP from accessing any service other than SMTP. It is also not intended for end-user/client PC usage, or to be used for "testing" purposes (without our prior consent.) If you are interested in using these list to help stop potential SPAM from reaching your inbox, speak with your email administrator/provider about their use of DNS Block Lists and mention this site to them. If you are simply interested in seeing if your email server IP(s) are listed, please use one of the many public sites available for just that purpose.
Under no circumstances (without our prior consent), are any type of scripted queries allowed. Such requests violate the usage policy.

USAGE: V4BL/FULL list is a commercial/pay-for-use service DNS IP registrations are requried. V4BL/FREE does not require a fee nor IP registration. The lists can be reached as typical UDP DNS IPv4 Block List access. (Lists can not be queried by FQDN, domain names, nor HELO/EHLO strings - Lists only reply to IPv4 address requests.)
Lists use standard UDP DNS only for ease of use (use via TCP DNS is not allowed and will fail). Lists respond to type A records (127.0.0.x), and TXT requests. Not all listed IPs may contain TXT records.(Do not use TXT record responses for listing/blocking purposes.) You must only use A records responses of 127.0.0.x for blocking. Abusive requestors will be denied! DNS admins must register thier external IP address with us and ensure that zone V4BL(Full) is not forwarded through any anonymous DNS servers/service. (Use of anonymous DNS services are only recommended for access to the V4BL/FREE Block List.)
We realize that the path you take to find our DNS service is entirely your choice; but understand that all paths are not created equal, nor are any paths guaranteed. For best results, one should use multiple DNS paths/servers. If accessing the V4BL/FREE Block List, the use of public DNS service paths is preferred; we recommended using DNS servers &
Block List DNS Domains: "Private FULL List" (codename:V4BL) and now "FREE.v4BL.org." (codename:V4BL-FREE) for unregistered/free access to a reduced subset of the larger list.

EXAMPLE: To run a simple test query on IP use "nslookup"
(You must reverse the IP address in your query where IP "ab.c.d.efg" becomes "efg.d.c.ab" as shown above.)

RESPONSES: There are five DNS returned results: Hit ",,," or miss "Non-existent domain"
If DNS response is "" then it's a match, the IP is listed for SPAM.
If DNS response is "" then it's a match, the IP is listed for rDNS, FCrDNS, or Domain issues.
If DNS response is "" then it's a match, the IP is listed for HACKING, exploited.
If DNS response is "" then it's a match, the IP is listed for SMTP AUTH abuse.
If DNS response is "Non-existent domain" then that IP is NOT listed.
If DNS response is "DNS request timed out." there may be a break in service or routing. If this continues, please let us know via email & include your source IP and DNS server IPs, they may have been intentionally blocked by us.
NOTE: An IP may return multiple codes (like " &")

CLARIFICATION: What defines abuse/misuse?
1. If your use does not originate from an actual non-commercial* inbound email IP reputation verification system, you are violating the usage policy.
2. If you make too many requests per second or per day, you may be violating the usage policy. Are you really checking emails? (see: rule 1)
3. If all your requests are only for IPs within specific subnets, you may be violating the usage policy. Again, are you really checking emails? (see: rule 1)
4. If any of your use is scripted, you may be violating the usage policy. Again, are you really checking emails? (see: rule 1)
5. If you don't understand how to follow one simple rule, don't bother re-reading rule 1 again, you are probably violating the usage policy and will be blocked.
6. If you are still reading this list, you should know that it really all comes down to just one simple rule (rule 1, if you haven't guessed.) Use these lists for non-commercial* inbound email IP reputation verification and you should be fine.
*commercial use is basically any resale of our lists/services, thus "profiting" from our lists/services without providing us with any compensation. (We strive to keep costs down to a bare minimum and access is generally provided free to most users but we do not exist to increase other businesses profit margins and will not be exploited for such; we exist to keep email inboxes clean and do so for the benefit of all those who work hard and don't have time to waste with SPAMkind.) If you are interested in a commercial* usage account, feel free to email us with your specific expected daily usage and we may then further discuss the opportunity.

But why can't we do any of those other things to this list? Because that takes up resources, resources that could be better used to keep real SPAM/JUNK emails out of real inboxes and not wasted on your servers asking our servers "Are we listed?... Are we listed?... Are we listed, yet?". Unless you really want the answer to be "yes", just stop asking the same question - over and over and over again.

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