Is the Invaluement blacklist still relevant for email deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 10 Aug 2025
Updated 19 Aug 2025
8 min read
Email blacklists (or blocklists) have long been a significant factor in email deliverability, often striking fear into the hearts of email marketers and system administrators. Being listed can mean your meticulously crafted messages end up in the spam folder or, worse, are rejected outright. The immediate consequence of being blacklisted is typically a substantial decline in your email delivery rate, directly impacting your sender reputation.
However, the landscape of email filtering has evolved considerably over the years. Modern mailbox providers, like Google and Yahoo, increasingly rely on complex internal algorithms, user engagement metrics, and authentication protocols (such as SPF, DKIM, and DMARC) rather than solely on third-party blacklists. This shift has led many to question the continued relevance of some older or less widely adopted blocklists.
One such blacklist that often comes up in discussions is Invaluement. It has been around for a while, and its name pops up in various deliverability contexts. So, the crucial question remains: Is the Invaluement blacklist still relevant for email deliverability today, or has its influence waned significantly?
Invaluement operates as a set of three distinct DNS-based blocklists (DNSBLs), each designed to identify and list different types of suspicious email sending behavior. These lists are often used as an additional layer of spam filtering by various email systems and service providers. Understanding their individual focus helps clarify their potential impact.
The three lists that comprise Invaluement are ivmURI, ivmSIP, and ivmSIP/24. ivmURI targets domains associated with spam, meaning if a domain used in a URL within an email is listed, it could trigger a block. ivmSIP focuses on individual IP addresses that are observed sending spammy content, while ivmSIP/24 extends this to block entire network ranges (/24 subnets) that are known for originating spam. This broader net can sometimes lead to innocent senders being caught if they share IP space with spammers.
Invaluement prides itself on identifying elusive spam, often focusing on bulk or low-engagement email activity, particularly relevant for business-to-business (B2B) mail streams. While not as universally relied upon as some of the larger, more prominent blacklists, its specialized approach means it can still play a role for specific receiving mail servers that choose to integrate its data into their filtering policies. Understanding how email blacklists actually work can help contextualize Invaluement's function.
Invaluement's lists at a glance
ivmURI: Lists domains found in the URI part of emails, typically those associated with spam campaigns.
ivmSIP: Identifies and lists individual IP addresses that are actively sending spam.
ivmSIP/24: A broader blocklist that flags entire /24 IP ranges that are heavily engaged in spam activities.
Evolution of blocklists and invaluement's place
In the past, blacklists held significantly more sway over email deliverability. A listing on almost any major blocklist would mean immediate and widespread delivery issues. However, the email ecosystem has matured. Mailbox providers today employ a multi-layered approach to spam filtering, where factors like sender reputation, email authentication (SPF, DKIM, DMARC), content analysis, and recipient engagement often carry more weight than a single blacklist listing.
This evolution means that a listing on a blocklist like Invaluement might not always manifest as universal email rejection. You might see a lower delivery rate to specific recipients, or your emails could be routed directly to the spam folder without an explicit bounce message. This can make it challenging to diagnose the impact if you're only looking at success logs from your Email Service Provider (ESP).
Despite the shift, it's a mistake to dismiss Invaluement entirely. While it may not impact giants like Gmail or Yahoo as heavily as it once did, many smaller or specialized Internet Service Providers (ISPs) and corporate mail filters still actively use its data. This means your emails could still be affected for a portion of your audience.
Modern mailbox provider filtering
Today's major mailbox providers (MBPs) leverage complex, dynamic systems to filter incoming mail.
Internal data: Primarily rely on their own historical data and user feedback.
Blacklist role: Public blacklists play a diminishing, secondary role in overall filtering decisions.
Invaluement's continuing relevance
While not a primary filter for all MBPs, Invaluement remains relevant for a specific segment.
Targeted impact: Affects delivery to ISPs and corporate mail servers that specifically subscribe to and use Invaluement data.
Granular rejection: Can still lead to hard bounces or spam folder placement for affected recipients.
Underlying issues: A listing often indicates a deeper sending hygiene problem that needs resolution.
Specific impact and use cases
Even if Invaluement doesn't cause a global deliverability meltdown, its impact on specific receiving systems can be notable. For instance, several providers have been known to use Invaluement for filtering, including major UK ISP BT Internet, and various security solutions or filtering services like FireEye Mimecast Barracuda, and MailRoute. If your audience includes recipients using these services, a listing can still lead to significant deliverability challenges for that segment. Some may reject mail at the gateway, while others might accept it but send it straight to spam.
The key here is understanding your specific audience and their receiving mail systems. If you're sending to a broad consumer base, a listing on Invaluement might have a lower overall impact compared to a listing on Spamhaus. However, if your campaigns are heavily focused on B2B or specific regional markets, then Invaluement could still pose a relevant threat to your inbox placement.
Ultimately, any blacklist listing, even if its direct impact isn't immediately apparent across all your sending metrics, signals an underlying issue with your email sending practices. It means that at least one system has identified your sending behavior as problematic enough to warrant a block. Ignoring such signals can lead to a gradual degradation of your overall sender reputation, eventually affecting even the major providers who might not directly use Invaluement.
Provider
Invaluement usage
BT Internet
Known to reject mail at the gateway based on Invaluement listings.
FireEye
Utilizes Invaluement for gateway rejection or spam filtering.
Mimecast
Integrates Invaluement data into its spam filtering algorithms.
Barracuda
Uses Invaluement as part of its multi-layered anti-spam defense system.
MailRoute
Employs Invaluement to help reject or quarantine suspicious emails.
Proactive management and removal strategies
Even if Invaluement doesn't cause widespread blocks for your specific sending profile, proactive monitoring is always a best practice. My recommendation is to consistently monitor your IP addresses and domains across a range of blocklists, not just the most commonly cited ones. You can use a blocklist checker tool to stay on top of your listings. Invaluement provides a delisting request page if you find yourself listed.
If you discover a listing on Invaluement (or any other blocklist), the first step isn't just requesting removal. You need to identify and rectify the underlying issue that led to the listing. This could involve an unexpected increase in bounce rates, sending to old or unengaged lists, issues with content, or compromised accounts. Simply getting delisted without addressing the root cause will likely lead to relisting.
A common sign of being listed on a blacklist like Invaluement is a bounce message indicating an ivmSIP or ivmURI block. It's crucial to analyze your bounce logs and understand why your emails are going to spam. Early detection of such bounces allows for quick action before the issue escalates.
Example of an Invaluement bounce messageplaintext
550 5.7.1 Service unavailable; Client host [X.X.X.X] blocked using ivmSIP;
See: http://www.invaluement.com/lookup/X.X.X.X
Invaluement might not be the most globally impactful blacklist for every sender, but its continued use by certain ISPs and corporate filters means it's not one to ignore. Maintaining a clean sending reputation requires constant vigilance, and understanding the nuances of how different blacklists operate is part of that process. Staying informed and proactive in your email blacklist management is key to ensuring consistent deliverability across all your recipient segments.
Views from the trenches
Best practices
Actively monitor your IP and domain reputation on a variety of blacklists, including specialized ones like Invaluement, to catch issues early.
Segment your audience and analyze deliverability metrics for different recipient domains to identify specific blocklist impacts.
Prioritize addressing the root cause of any listing, such as high bounce rates or low engagement, before requesting delisting.
Common pitfalls
Assuming that Invaluement is irrelevant because major mailbox providers may not rely on it as heavily.
Focusing solely on global deliverability metrics and overlooking specific ISP or corporate domain blocking due to Invaluement listings.
Requesting removal from Invaluement without first identifying and fixing the underlying issues that led to the listing.
Expert tips
Use comprehensive log analysis to identify specific bounce codes or rejections that reference Invaluement, providing clear evidence of impact.
Engage directly with Invaluement or the affected mail provider to understand the specific reason for listing and facilitate removal, if necessary.
Regularly review and clean your mailing lists to reduce spam trap hits and improve overall sending hygiene, which can prevent future listings.
Marketer view
Marketer from Email Geeks says: While the Return Path article indicated a high impact from Invaluement, my own deliverability statistics with my ESP did not reflect this, leading me to question its current relevance.
2018-09-27 - Email Geeks
Marketer view
Marketer from Email Geeks says: Invaluement was used by BT Internet to reject emails as recently as August 2017, which is important for updating historical information.
2018-09-28 - Email Geeks
The bottom line
The question of Invaluement's relevance isn't a simple yes or no. Its role has indeed shifted in the broader deliverability landscape, with major players relying less on public blacklists. However, it continues to be a factor for a significant segment of email recipients, particularly those using specific ISPs or corporate filtering solutions.
For your email program, this means Invaluement should not be ignored. A listing on any of its sub-lists (ivmURI, ivmSIP, ivmSIP/24) indicates a problem that, even if not universally impactful, affects a portion of your audience and points to potential underlying issues with your sending practices.
Ultimately, maintaining strong email deliverability is about continuous monitoring, understanding complex filtering mechanisms, and consistently adhering to best practices. Invaluement remains a piece of that puzzle, demanding attention when your IPs or domains are listed. Staying proactive ensures your messages reach their intended recipients, regardless of the evolving email security landscape.
Spamhaus
0Spam
Cisco
NoSolicitado
URIBL
abuse.ro
ALPHANET
Anonmails
Ascams
BLOCKEDSERVERS
Calivent Networks
EFnet
JustSpam
Kempt.net
NordSpam
RV-SOFT Technology
Scientific Spam
Spamikaze
SpamRATS
SPFBL
Suomispam
System 5 Hosting
Team Cymru
Validity
www.blocklist.de Fail2Ban-Reporting Service
ZapBL
2stepback.dk
Fayntic Services
ORB UK
technoirc.org
TechTheft
Yahoo as heavily as it once did, many smaller or specialized Internet Service Providers (ISPs) and corporate mail filters still actively use its data. This means your emails could still be affected for a portion of your audience.
BT Internet, and various security solutions or filtering services like 
FireEye
Mimecast
Barracuda, and 
MailRoute. If your audience includes recipients using these services, a listing can still lead to significant deliverability challenges for that segment. Some may reject mail at the gateway, while others might accept it but send it straight to spam.
