What are best practices for managing bounced, unsubscribed, and spam-complaint users in email marketing?
Matthew Whittaker
Co-founder & CTO, Suped
Published 26 Apr 2025
Updated 19 Aug 2025
8 min read
Effectively managing bounced emails, unsubscribes, and spam complaints is critical for maintaining a healthy sender reputation and ensuring your messages reach the inbox. Ignoring these vital aspects can lead to poor deliverability, blocklistings (or blacklistings), and ultimately, a significant impact on your email marketing ROI. It's not just about removing bad addresses, but also about understanding the underlying reasons and implementing proactive strategies to prevent future issues.
Understanding the impact on deliverability
Bounced emails are messages that couldn't be delivered to the recipient. They fall into two main categories: hard bounces and soft bounces. Hard bounces, such as a nonexistent email address or a permanently closed account, indicate a permanent delivery failure. Soft bounces, like a full inbox or a temporary server issue, suggest a temporary problem that might resolve itself. Promptly identifying and handling both types is essential for maintaining a clean email list.
Unsubscribes occur when recipients no longer wish to receive your emails. While it might seem negative, an unsubscribe is actually a healthy sign of a well-managed list. It indicates that recipients have a clear way to opt out, rather than marking your emails as spam. Providing an easy and prominent unsubscribe mechanism is not only a best practice but also a legal requirement in many regions, such as under CAN-SPAM and GDPR regulations.
Spam complaints are the most damaging feedback for your sender reputation. When a recipient marks your email as spam, internet service providers (ISPs) take notice. A high complaint rate signals to ISPs that your emails are unwanted, leading to your domain or IP being blocklisted (or blacklisted). Monitoring your complaint rate and acting swiftly is crucial, as even a small percentage, like above 0.1%, can severely impact your deliverability. You can refer to Customer.io's deliverability best practices for more on this.
Managing bounces effectively
When an email bounces, your system should automatically record the bounce type and update the subscriber's status. For hard bounces, immediate removal from your active sending list is non-negotiable. Sending to hard-bounced addresses repeatedly can quickly damage your sender reputation and lead to penalties from ISPs. It also wastes resources and makes your list hygiene look poor to mailbox providers.
Soft bounces require a more nuanced approach. Instead of immediate removal, you can set up a retry sequence for a limited number of attempts or a specific duration. If the email continues to soft bounce after these retries, consider suppressing the address. Many email service providers (ESPs) handle this automatically, but it is important to understand how soft bounces affect sender reputation. Regular monitoring of your bounce rates is essential, as consistently high rates signal underlying issues with your list quality or sending practices. You can learn more about cleaning up soft bounces.
Hard bounces
Immediate suppression is required. These emails indicate permanent issues, such as invalid addresses. Continued attempts to send to them will harm your sender reputation and potentially lead to your domain or IP being added to a blocklist.
Impact: Directly affects sender reputation and deliverability.
Automated bounce handling processes are common with most ESPs, which will automatically suppress hard bounces and manage soft bounce retries. However, it is always a good practice to manually review bounce reports periodically, especially if you notice a sudden spike in bounce rates. This can help identify larger issues, such as outdated list segments or issues with a specific domain. For detailed strategies, review ultimate guides to email bounce rate management.
Handling unsubscribes with grace
Provide a clear and easy unsubscribe link in all your marketing emails. This link should ideally be a one-click unsubscribe, streamlining the process for the user. Making it difficult to unsubscribe frustrates recipients, increasing the likelihood of them marking your emails as spam, which is far worse for your sender reputation than an unsubscribe. ISPs (like Gmail and Yahoo) prefer clear unsubscribe options, and it's a key factor in their filtering algorithms.
Once a user unsubscribes, immediately remove them from all active mailing lists. Most email platforms handle this automatically, moving the address to a suppression list. This ensures that you don't accidentally send them emails in the future, which can lead to spam complaints and legal repercussions. Maintaining a suppression list is also crucial for compliance purposes, providing a record that the user opted out.
A common question arises when a user unsubscribes and then later resubscribes (especially via double opt-in). Mailbox providers like Gmail and Yahoo prioritize user intent. If a user explicitly resubscribes, especially with a confirmed opt-in process, it indicates they genuinely want your emails, and sending to them again typically won't negatively impact your deliverability. The key is true consent and honoring past requests unless a new, explicit consent is given. Learn more about 1-click versus 2-click unsubscribes.
Minimizing spam complaints
The most effective way to minimize spam complaints is to ensure you only send emails to users who have explicitly opted in and who expect to receive your content. Implementing a confirmed opt-in (also known as double opt-in) process, where users must confirm their subscription, is highly recommended. This prevents accidental sign-ups and spam traps, drastically improving your list quality. Strategies to reduce email spam complaints often emphasize this.
Beyond the opt-in process, consistent engagement and relevant content are key. Send emails with valuable information that aligns with what your subscribers signed up for. Segment your audience to send targeted messages, reducing the likelihood of users feeling overwhelmed or receiving irrelevant content. Regularly prune your email list by identifying and removing unengaged subscribers who haven't opened or clicked your emails in a significant period. This practice, often called list hygiene, is essential for maintaining a healthy sender reputation. You can read more about managing unengaged subscribers.
Actively monitor your spam complaint rates through your ESP's analytics or ISP feedback loops (e.g., Google Postmaster Tools). If you see a spike, investigate immediately. This could indicate a problem with a recent campaign, a change in audience expectations, or even a phishing attack targeting your domain. Prompt action, including pausing campaigns to affected segments or domains, can mitigate long-term damage to your sender reputation. For overall guidance, consider Microsoft's guidelines on content.
Data retention and re-engagement
The question of whether to delete bounced, unsubscribed, or spam-complaint records from your database or simply mark them as do not email is complex. While deleting them might seem like a way to clean your database, it can lead to accidental re-subscribes of previously problematic addresses if not handled thoroughly across all data sources. Many experts recommend retaining these records on a suppression list.
Retain on suppression list
Keeping bounced, unsubscribed, and spam-complaint records on a suppression list (rather than deleting them) ensures you don't accidentally re-add them, even if they try to resubscribe without proper consent. This is particularly important during platform migrations. Handling permanent bounce errors is a crucial aspect of this approach.
Pros: Prevents accidental re-engagement with non-consenting users. Provides a clear audit trail for compliance. Can honor legitimate re-subscriptions via double opt-in.
Cons: Increases database size. May require careful management to ensure these lists are not accidentally included in active sends.
Delete from database
Deleting records reduces the amount of personally identifiable information (PII) you hold, which can minimize data security risks and compliance burdens, especially under strict privacy regulations. However, it requires a robust process to ensure complete removal across all systems.
Pros: Reduces PII storage and associated security/compliance risks. Keeps active database cleaner.
Cons:Risk of re-adding bad data if not synchronized across all platforms. Potential loss of historical data for analysis or compliance purposes.
Regardless of your approach, consistent list cleaning and hygiene are paramount. This includes regularly reviewing engagement metrics, segmenting inactive users for potential re-engagement campaigns (and then removing them if they remain unresponsive), and maintaining detailed records of consent and suppression. Keeping a clean and engaged list is highlighted by Attentive's recommendations on deliverability. This proactive management prevents deliverability issues down the line.
Views from the trenches
Best practices
Always suppress hard bounces immediately and permanently from your active sending lists.
Implement double opt-in for all new subscribers to ensure explicit consent and reduce spam complaints.
Provide a prominent and easy-to-use one-click unsubscribe link in every email.
Maintain a dedicated suppression list for unsubscribes and spam complaints.
Regularly monitor your bounce rates, unsubscribe rates, and spam complaint rates.
Common pitfalls
Deleting records of bounced or unsubscribed users without maintaining a separate suppression list, risking accidental re-subscription.
Ignoring soft bounces, which can accumulate and negatively impact your sender reputation over time.
Making it difficult for users to unsubscribe, leading to increased spam complaints.
Sending emails to purchased or old, unverified lists, which often contain spam traps and invalid addresses.
Not segmenting your audience and sending irrelevant content to a broad list, leading to disengagement.
Expert tips
Consider archiving old, unengaged subscriber data separately to minimize PII risks while still retaining a record of their history.
Automate your bounce and unsubscribe handling as much as possible through your email service provider (ESP) features.
If a user resubscribes via a legitimate double opt-in process after unsubscribing, it is generally safe to resume sending, as mailbox providers prioritize current user intent.
Focus on content relevance and list segmentation to naturally reduce complaints and keep subscribers engaged.
Review your email acquisition methods regularly to ensure they align with best practices and legal requirements.
Marketer view
A marketer from Email Geeks says that they suppress bounced and spam-complaint users, and if those users resubscribe via double opt-in, they honor the new subscription. Keeping a record is a good practice and may even be legally required, so consulting with a legal team is always advised.
2024-11-20 - Email Geeks
Expert view
An expert from Email Geeks says that from a database perspective, deleting records is generally a bad practice. Archiving records is easy and storage is inexpensive, and it prevents bad data from re-entering the active system if users are accidentally re-added or resubscribe without a proper process.
2024-11-21 - Email Geeks
Key takeaways for deliverability
Proactive management of bounced emails, unsubscribes, and spam complaints is not merely a technical task, but a fundamental aspect of successful email marketing. By consistently cleaning your lists, respecting user preferences, and delivering valuable content, you not only improve your sender reputation and deliverability but also build stronger, more trusting relationships with your audience. This holistic approach ensures your email program remains effective and compliant.
