What are the pros and cons of maintaining a list of domains and role addresses to never send emails to?
Matthew Whittaker
Co-founder & CTO, Suped
Published 24 May 2025
Updated 17 Aug 2025
8 min read
Maintaining an exclusion list of domains and role addresses that you should never send emails to seems like a straightforward way to protect your sender reputation. The idea is simple: prevent messages from ever reaching known problematic recipients, thus avoiding bounces, spam complaints, or hitting spam traps.
However, like many aspects of email deliverability, the reality is more nuanced than it appears. While there are clear benefits to a careful approach, relying too heavily on such a list can also introduce unexpected challenges and potentially mask deeper issues with your sending practices or list acquisition methods.
The case for a proactive suppression list
The primary motivation behind creating a never send list is to safeguard your sender reputation and ensure email deliverability. Certain email addresses, such as abuse@, postmaster@, or webmaster@, are known as role-based email addresses. These are typically not associated with individual users but rather with organizational functions. Sending marketing or even transactional emails to these can lead to high bounce rates, spam complaints, and damage to your sender score. Mailbox providers often flag senders who repeatedly hit these addresses.
Risks of role-based addresses
Role-based email addresses are generally discouraged for bulk sending due to several risks, as highlighted by Klaviyo's insights on their impact. They often do not opt-in to receive emails and can have high spam complaint rates, significantly impacting your sender reputation. For a comprehensive understanding of managing these, consider exploring resources on how to manage role-based addresses for suppression filters.
High bounce rates: Many role-based addresses are configured as catch-all accounts or simply do not have an active human monitoring them for marketing emails, leading to hard bounces.
Spam complaints: Recipients of role-based emails are more likely to mark unwanted mail as spam, especially if they haven't explicitly subscribed. This directly harms your sender score and can lead to your IP or domain being put on a blocklist (or blacklist).
Spam traps: Some role-based addresses are repurposed as spam traps. Sending to these can severely damage your domain reputation and lead to immediate blacklisting, preventing future emails from reaching their intended inboxes.
Similarly, certain domains are notorious for hosting spam traps or for being general sources of poor engagement, such as free email providers like outlook.com or yahoo.com when they are used for non-personal accounts. While it's generally not advisable to broadly block these legitimate services, identifying specific patterns or subdomains that consistently result in negative outcomes can be beneficial. Public blocklists (or blacklists) can offer a starting point, but a nuanced approach is always required. It is important to know the difference between public and private blacklists before implementing any domain-level blocking.
By proactively preventing sends to these known problematic addresses and domains, you can mitigate many immediate risks to your email program. This strategy aims to avoid the negative signals that can trigger spam filters or lead to a domain or IP blocklist (or blacklist), ultimately contributing to better inbox placement rates.
Benefits of a domain and role address exclusion list
Implementing a never send list, particularly for role-based addresses and domains known for spam traps, offers several tangible benefits to your email marketing efforts. First and foremost, it directly reduces your bounce rate. High bounce rates signal to mailbox providers that your list hygiene is poor, which can negatively impact your sender reputation. By pre-emptively removing these addresses, you maintain a cleaner, more engaged subscriber list. This also includes avoiding spam traps from Wi-Fi generated lists.
Action
Potential outcome
Sending to known spam traps or blocklisted domains
Immediate and severe damage to sender reputation, leading to domain or IP blocklisting (or blacklisting).
Sending to general role-based addresses (e.g., info@, sales@)
Increased spam complaint rates and bounces, degrading sender reputation over time.
Furthermore, a never send list can act as a barrier against malicious list sign-ups or attempts at list poisoning. Bad actors might intentionally subscribe problematic addresses to your lists to disrupt your sending. By filtering these at the point of entry or before sending, you protect your email infrastructure and maintain the integrity of your marketing data. This proactive step helps ensure your email deliverability remains consistent and reliable.
Finally, such a list can help focus your email efforts on legitimate, engaged subscribers. When you eliminate known problematic addresses and domains from your sending queue, you allocate resources more effectively. This means your emails are more likely to reach people who genuinely want to receive them, leading to higher open rates, click-through rates, and ultimately, better return on investment from your email campaigns. It’s a way to ensure your efforts are not wasted on unconvertible or harmful contacts.
Disadvantages and pitfalls of maintaining a blocklist
Despite the apparent advantages, maintaining a rigid never send list comes with notable drawbacks. One significant risk is blocking legitimate recipients. It's not uncommon for role-based addresses (like support@ or billing@) to be used for transactional or essential communications by actual users. If you indiscriminately block all such addresses, you risk preventing critical emails like order confirmations, password resets, or important customer service updates from reaching their intended recipients, leading to frustration and potential business loss. As recounted in a Spam Resource blog post from 2003, even well-intentioned blocking can backfire, affecting legitimate mail flow.
Proactive blocking
Immediate protection: Prevents sends to known problematic addresses, reducing immediate risks of hitting spam traps or generating complaints.
Simplicity: Once set up, it can appear to automate some aspects of deliverability management.
Cons
False positives: Risk of blocking legitimate subscribers or important communications.
Masks issues: Can hide underlying problems with list acquisition or engagement, preventing necessary operational improvements. You may not even realize issues with sending to old email lists.
Maintenance burden: Requires continuous updates and monitoring to remain effective and avoid unintended blocks.
Reactive monitoring and correction
Root cause analysis: Allows you to identify why problematic addresses are entering your system and address the source.
Flexibility: Ensures all legitimate emails, even to unusual addresses, are delivered.
Cons
Initial impact: May experience temporary dips in deliverability as you identify and clean problematic addresses.
Requires robust monitoring: Needs effective tools for blocklist monitoring and performance analysis. This can be complex, and some services will over-report your email deliverability rate to make themselves look better.
Furthermore, a strictly enforced blacklist can mask deeper deliverability problems. If your email program is generating a high number of spam complaints or hitting spam traps, simply blocking those specific addresses won't solve the underlying issue. It might be a sign of poor list acquisition practices, irrelevant content, or a lack of proper consent. Silently filtering these bad signals means you miss out on crucial feedback that could help you improve your overall email strategy. It is critical to know what happens when your domain is on a blacklist, and it's much better to avoid it in the first place.
Finally, maintaining a comprehensive never send list is a continuous effort. Domains and role addresses can change, and new problematic entities emerge regularly. Relying on static lists means you'll constantly be behind, or you might find yourself inadvertently blocking legitimate contacts as their usage patterns evolve. This maintenance burden can outweigh the perceived benefits, especially for senders with dynamic or very large email lists. It is critical to stay up to date and know what email backscatter is and how to stop it, to ensure you are not listed by a blocklist (or blacklist).
Better strategies for maintaining email deliverability
Rather than focusing solely on a never send list, a more robust approach to email deliverability involves prioritizing consent, list hygiene, and continuous monitoring. The foundation of good deliverability is building your email list through clear, explicit permission. Double opt-in, for instance, verifies that subscribers genuinely want to receive your emails, significantly reducing the likelihood of hitting spam traps or generating complaints from uninterested recipients. This also means you don't have to manage a tricky allowlist, and know when domains should be allowlisted.
Regular list cleaning: Periodically remove inactive or invalid addresses to improve engagement and reduce bounces. This includes knowing what email domains and addresses to avoid.
Monitor engagement metrics: Track open rates, click-through rates, and complaint rates to identify and address issues early. Utilizing tools for DMARC monitoring and blocklist monitoring can provide valuable insights.
Segment your audience: Send targeted content to different groups to improve relevance and reduce opt-outs. This will directly improve your domain reputation and help ensure your emails land in the inbox.
Authenticate your emails: Proper configuration of SPF, DKIM, and DMARC is fundamental for trust.
Beyond these foundational practices, consider employing advanced email validation services that can identify and remove problematic addresses from your list without you having to manually maintain a blacklisted (or blocklisted) domain and address list. These services often use sophisticated algorithms to detect spam traps, invalid addresses, and known complainers, allowing you to clean your list proactively and automatically. This helps avoid strategic considerations for email list validation and alternative approaches.
Ultimately, the goal is to cultivate a healthy email ecosystem where your messages are welcomed, not filtered. By focusing on building quality lists and delivering relevant content, you naturally reduce the need for extensive never send lists. Trust and permission are your most powerful tools in ensuring your emails consistently reach the inbox.
Balancing protection with deliverability
When deciding whether to maintain a never send list, it's crucial to balance the desire for protection against the potential for over-filtering and missed opportunities. While proactively avoiding known bad actors and risky role addresses can prevent immediate harm to your sender reputation, it's not a substitute for fundamental deliverability best practices.
The most effective long-term strategy involves cultivating a healthy email list through strong consent mechanisms, regular hygiene, and continuous monitoring of your email performance. This approach addresses the root causes of deliverability issues, rather than just masking the symptoms. By doing so, you build a resilient email program that naturally avoids problematic addresses and ensures your messages reach engaged recipients.
Views from the trenches
Best practices
Always prioritize strong consent-based list building, such as double opt-in, to minimize problematic addresses from the start.
Regularly clean your email lists to remove inactive users and hard bounces, as this naturally reduces risk.
Focus on content relevance and segmentation to keep subscribers engaged and reduce spam complaints.
Common pitfalls
Relying solely on a `never send` list can mask deeper issues with your list acquisition or sending practices.
Indiscriminately blocking all role-based addresses can prevent legitimate transactional emails from being delivered.
Failure to regularly update your `never send` list can lead to outdated information and missed opportunities.
Expert tips
Use comprehensive email validation services to proactively identify and remove high-risk addresses.
Monitor your sender reputation metrics (bounces, complaints, spam trap hits) to identify issues rather than just blocking them.
Educate your sending teams on the importance of list quality and permission to avoid generating problematic addresses.
Expert view
Expert from Email Geeks says that a "never send to" domain list is often unnecessary if proper permission practices are in place.
2024-02-16 - Email Geeks
Expert view
Expert from Email Geeks says that allowing senders to experience consequences can highlight and address root causes of deliverability issues rather than silently fixing problems.
outlook.com or 
yahoo.com when they are used for non-personal accounts. While it's generally not advisable to broadly block these legitimate services, identifying specific patterns or subdomains that consistently result in negative outcomes can be beneficial. Public blocklists (or blacklists) can offer a starting point, but a nuanced approach is always required. It is important to know the difference between public and private blacklists before implementing any domain-level blocking.
