Are email list cleaning services useful for improving email deliverability, and how do they work?

Summary

The usefulness of email list cleaning services for improving email deliverability is a debated topic. While marketers and documentation often portray them as tools that enhance deliverability by removing invalid, inactive, and harmful email addresses, reducing bounce rates, and preventing spam complaints, experts from Email Geeks and Word to the Wise express skepticism. They argue that these services often mask underlying problems with data collection practices and are not a solution for fundamentally flawed or 'polluted' lists. The experts suggest that a comprehensive approach involving data analysis, deliverability efforts, and list segmentation is more effective. Concerns are also raised about the ethical practices of some list cleaning vendors. Overall, the consensus is that while list cleaning services may offer some benefits, they should not be relied upon as a primary solution for improving deliverability, and addressing the root causes of data quality issues is crucial.

Key findings

  • Differing Perspectives: Marketers and documentation tend to view list cleaning as a positive tool, while experts express skepticism.
  • Limited Effectiveness for Polluted Lists: List cleaning is not considered effective for fixing fundamentally flawed or polluted lists.
  • Masking Underlying Issues: List cleaning services often mask underlying problems with data collection practices rather than solving them.
  • Potential Benefits: List cleaning may reduce bounce rates, prevent spam complaints, and improve sender reputation, according to some sources.
  • Comprehensive Approach Needed: Experts suggest a comprehensive approach involving data analysis, deliverability efforts, and list segmentation is more effective.
  • Ethical Concerns with Vendors: Concerns are raised about the ethical practices of some list cleaning vendors, including the acquisition and use of data.

Key considerations

  • Data Collection Practices: Focus on improving data collection practices to prevent list pollution in the first place.
  • Thorough Evaluation: Thoroughly evaluate the state of your email list to determine if cleaning is even necessary.
  • Comprehensive Strategy: A comprehensive email marketing strategy is required, not just a single list cleaning action.
  • Vendor Due Diligence: Exercise due diligence when selecting a list cleaning vendor, considering their reputation and practices.
  • Addressing Root Causes: Prioritize addressing the root causes of data quality issues over relying solely on list cleaning.
  • Realistic Expectations: Have realistic expectations about what list cleaning can achieve, recognizing that it's not a silver bullet.

What email marketers say
9Marketer opinions

Email list cleaning services are marketed as a solution to improve email deliverability by removing invalid, inactive, or harmful email addresses from a sender's list. This process aims to reduce bounce rates, avoid spam traps, protect sender reputation, and prevent penalties from ESPs. Ultimately, the goal is to ensure that emails reach engaged subscribers, leading to better open rates, click-through rates, conversions, and overall ROI.

Key opinions

  • Core Promise: List cleaning services promise better email deliverability and improved inbox placement.
  • How It Works: Cleaning involves identifying and removing invalid addresses, spam traps, complainers, and inactive users.
  • Key Benefits: Improved sender reputation, reduced bounce rates and spam complaints, and higher engagement metrics are observed after cleaning.
  • Impact on ROI: Cleaning lists leads to better ROI by focusing marketing efforts on engaged subscribers who are more likely to convert.
  • ISP Engagement: Removing inactive subscribers is crucial as ISPs consider engagement a key factor in determining deliverability.
  • Consistent List Hygiene: Maintaining consistent list hygiene ensures a higher percentage of emails reach engaged subscribers, which improves sender reputation over time.

Key considerations

  • Invalid Addresses: Removing invalid addresses is essential to reduce bounce rates and improve deliverability.
  • Spam Traps: Avoiding spam traps is vital to protecting sender reputation.
  • Inactive Users: Removing inactive users helps focus marketing efforts on engaged subscribers.
  • Sender Reputation: Maintaining a positive sender reputation is key to ensuring emails reach the inbox.
  • Compliance: Email list cleaning helps avoid penalties from ESPs by adhering to best practices and compliance standards.
  • List Collection Practices: Cleaning a list is only as good as your original collection practices - consider this as part of your overall process.
Marketer view

Email marketer from Webdew explains that if emails are being sent to many inactive users who do not open or engage with them, ISPs may start to view the sender as a source of unwanted emails. Email List cleaning helps to remove the unwanted emails and therefore helps in maintaining a good sender reputation.

July 2021 - Webdew
Marketer view

Email marketer from ActiveCampaign answers that email list cleaning is important to get rid of old addresses, inactive users and those that could mark emails as spam, which can result in low deliverability and sender reputation.

January 2023 - ActiveCampaign
Marketer view

Email marketer from Email Marketing Forum user 'EmailPro22' states maintaining consistent list hygiene is essential for sustained deliverability. Regularly cleaning lists to remove bounces and inactive users ensures a higher percentage of emails reach engaged subscribers, improving sender reputation over time.

December 2023 - Email Marketing Forum
Marketer view

Email marketer from Litmus shares that cleaning email lists increases ROI by focusing on engaged subscribers, leading to better open rates, click-through rates, and conversions. It ensures that marketing efforts are directed toward those most likely to respond positively.

October 2023 - Litmus
Marketer view

Email marketer from NeverBounce shares that to clean an email list, you should identify and remove invalid addresses, spam traps, and complainers. This process enhances deliverability and helps avoid penalties from ESPs.

August 2021 - NeverBounce
Marketer view

Email marketer from Reddit user u/EmailExpert explains that cleaning inactive subscribers is crucial because ISPs use engagement as a key factor in determining deliverability. Removing unengaged users improves the overall sender reputation.

July 2021 - Reddit
Marketer view

Email marketer from Email Hippo shares that email verification and cleaning can improve deliverability by removing invalid addresses, reducing bounce rates, avoiding spam traps, and protecting sender reputation. This leads to better engagement and ROI.

January 2024 - Email Hippo
Marketer view

Email marketer from Hunter.io explains that list cleaning allows for identifying and removing addresses that are invalid, disposable, role-based, or likely to generate spam complaints, thus improving deliverability and sender reputation.

January 2023 - Hunter.io
Marketer view

Email marketer from Wordable explains that the core promise of list cleaning services is better email deliverability, reaching more inboxes and less spam folders.

June 2022 - Wordable

What the experts say
16Expert opinions

Experts generally express skepticism about the value of email list cleaning services, particularly for fundamentally flawed or 'polluted' lists. They argue that these services often mask underlying problems with data collection practices rather than solving them. While list cleaning might offer temporary relief or be useful in very specific situations (e.g., avoiding ESP bounce-related penalties), experts emphasize that a comprehensive approach involving data analysis, deliverability efforts, and potentially aggressive list segmentation is necessary for truly cleaning a problematic list. There is a concern that many list cleaning services employ unethical tactics or provide inaccurate data. A select few vendors, like Kickbox, are perceived as less unethical, but still, their overall benefit is debated. Ultimately, focusing on improving data collection practices is considered more effective than relying solely on list cleaning services.

Key opinions

  • Limited Effectiveness: List cleaning services are generally not effective for fixing fundamentally bad lists or retrieving significantly polluted lists.
  • Masking Problems: These services primarily hide symptoms rather than address the root causes of deliverability issues.
  • Unethical Practices: Many list cleaning services engage in questionable or unethical practices, including buying data from questionable sources or using spam tactics.
  • Alternative Solutions: A better approach to cleaning a list often involves data audit, statistical analysis, and ongoing deliverability efforts.
  • Data Accuracy: The data provided by list cleaning services may not be accurate or useful in addressing underlying list problems.
  • Specific Use Cases: List cleaning may be useful in specific situations, such as avoiding penalties from ESPs due to high bounce rates or fixing data entry typos, rather than making the list 'healthier'

Key considerations

  • Data Collection Practices: Focus on improving data collection practices to prevent list pollution in the first place.
  • Comprehensive Approach: Cleaning a list requires a comprehensive strategy, including data analysis, deliverability monitoring, and list segmentation.
  • Ethical Concerns: Be wary of list cleaning services that engage in unethical tactics or make unrealistic promises.
  • Vendor Selection: Carefully vet list cleaning vendors and consider their reputation and practices before using their services.
  • Underlying Issues: Address the underlying issues causing deliverability problems, rather than relying solely on list cleaning.
  • Signal Removal: Understand that list cleaning removes signals of a polluted list but doesn't fix the underlying issue.
Expert view

Expert from Email Geeks says list cleaning services are a waste of money. if you’ve mailed the polluted list one time you’ve done the bulk of the work they do.

October 2021 - Email Geeks
Expert view

Expert from Email Geeks explains that if a list got polluted, you need to get rid of all the pollution, not just fish out the giant turds floating in the pond. And if you fish out the giant turds do you still want to drink the punch?

February 2025 - Email Geeks
Expert view

Expert from Email Geeks says Kickbox is the only vendor in the space that’s convinced me they’re not unethical scum. (They’ve not convinced me that they’re actually going to benefit their users in many cases, but they’ll do minimal harm to anyone other than their customer and potential users of the service are usually happy to accept “this might not help a lot, or even at all”).

May 2022 - Email Geeks
Expert view

Expert from Email Geeks explains that that doesn’t mean the data they provide is entirely useless, but using it to remove emails from the list isn’t going to help with underlying issues.

March 2022 - Email Geeks
Expert view

Expert from Word to the Wise states if a list got polluted, you need to get rid of all the pollution, not just fish out the giant turds floating in the pond. If you fish out the giant turds do you still want to drink the punch?

January 2024 - Word to the Wise
Expert view

Expert from Email Geeks shares I spent an hour on the phone with Jack before they launched talking about their goals and what they were doing and how they were doing it and their company philosophy. I’ve talked with (and consulted for) a number of other vendors in the space (there was a point they were getting blocked for abusive behavior and wanted help getting unblocked and came to me).

December 2021 - Email Geeks
Expert view

Expert from Email Geeks states list cleaning cannot help with a fundamentally strong list that got polluted.

January 2023 - Email Geeks
Expert view

Expert from Email Geeks states list cleaning cannot help with a fundamentally strong list that got polluted.

January 2023 - Email Geeks
Expert view

Expert from Email Geeks explains that list cleaning services are not going to get a sender out of a hole, though it may hide some of the symptoms for a while.

March 2023 - Email Geeks
Expert view

Expert from Email Geeks explains that the point of list cleansing services is take a list that’s been gathered badly and will cause problems and remove the most obvious signals that you can use to identify those problems. Once it’s done your list is still bad, but you’ve hidden the data that you, or your ESP, might use to diagnose that.

November 2024 - Email Geeks
Expert view

Expert from Word to the Wise explains the point of list cleansing services is to take a list that’s been gathered badly and will cause problems and remove the most obvious signals that you can use to identify those problems. Once it’s done your list is still bad, but you’ve hidden the data that you, or your ESP, might use to diagnose that.

December 2023 - Word to the Wise
Expert view

Expert from Email Geeks explains that it is possible to clean a polluted list, but it’s something you do with audit data analysis, statistics, ongoing deliverabilty efforts and a willingness to carve out chunks with a vigorous machete. It’s not something you can do by sending a CSV and three grand in non-sequential bills to a list cleansing vendor.

January 2022 - Email Geeks
Expert view

Expert from Word to the Wise shares that bounces are a signal that your list collection practices are getting inaccurate data. List washing bounces removes the signal. It does not fix the fact that your data is inaccurate.

April 2022 - Word to the Wise
Expert view

Expert from Word to the Wise explains that many of the providers are abusive in their tactics (buying data from ESPs who have told GDPR they are not data controllers or actual spammers or doing partial SMTP transactions). Some of the providers outright lie.

April 2024 - Word to the Wise
Expert view

Expert from Email Geeks says list cleaning is useful if it’s “no legit ESP will mail my lists because they bounce”. But if it’s more like what you’d think of as “will it make my legit, not terrible email programme healthier and more effective?“, probably not.

July 2022 - Email Geeks
Expert view

Expert from Email Geeks shares that I’ve never recommended them to any client and have never needed that information to actually clean up a list.

February 2022 - Email Geeks

What the documentation says
4Technical articles

Email list cleaning services, according to documentation from various providers (SendGrid, ZeroBounce, Kickbox, and Mailchimp), improve email deliverability by removing invalid, inactive, or harmful email addresses. This process reduces bounce rates and spam complaints, which are essential factors in maintaining a positive sender reputation. List cleaning also often includes syntax checks, domain validation, mailbox existence verification, and spam trap detection. The result is a healthier email list, better campaign performance, and improved engagement metrics.

Key findings

  • Deliverability Improvement: List cleaning improves email deliverability by removing problematic email addresses.
  • Reduced Bounce Rates: Removing invalid addresses reduces bounce rates, positively impacting sender reputation.
  • Fewer Spam Complaints: List cleaning reduces the likelihood of spam complaints, which are detrimental to sender reputation.
  • Process Components: Email verification involves syntax checks, domain validation, mailbox existence verification, and spam trap detection.
  • Healthier Lists: List cleaning leads to healthier email lists with better campaign performance.
  • Improved Engagement: Improved engagement metrics because of increased focus on active and valid subscribers.

Key considerations

  • Invalid Addresses: Identify and remove invalid email addresses to reduce bounce rates.
  • Inactive Contacts: Remove inactive contacts to improve engagement metrics.
  • High-Risk Contacts: Identify and remove high-risk contacts to avoid spam complaints.
  • Sender Reputation: Maintain a positive sender reputation by minimizing bounces and spam complaints.
  • Verification Process: Implement a robust email verification process to ensure the validity of email addresses.
  • Campaign Performance: Monitor campaign performance to gauge the effectiveness of list cleaning efforts.
Technical article

Documentation from ZeroBounce explains that email verification improves deliverability by removing invalid and risky email addresses, reducing bounce rates, and preventing spam complaints. This helps maintain a positive sender reputation.

June 2022 - ZeroBounce
Technical article

Documentation from Kickbox states that the email verification process involves syntax checks, domain validation, mailbox existence verification, and spam trap detection to ensure deliverability and improve sender reputation.

June 2022 - Kickbox
Technical article

Documentation from Mailchimp recommends using a email list cleaning service to identify and remove invalid, inactive, or high-risk contacts can greatly improve deliverability rates and engagement metrics. This helps reduce bounce rates and spam complaints, leading to a healthier list and better campaign performance.

April 2023 - Mailchimp
Technical article

Documentation from SendGrid explains that list cleaning removes invalid, inactive, or harmful email addresses, reducing bounce rates and spam complaints, which are key factors in maintaining a good sender reputation and improving deliverability.

October 2024 - SendGrid