What is an acceptable bounce rate threshold and how does it affect sender reputation?
Michael Ko
Co-founder & CEO, Suped
Published 20 May 2025
Updated 16 Aug 2025
6 min read
Email bounce rates are a critical metric for anyone sending emails, whether for marketing, transactional, or informational purposes. They represent the percentage of emails that could not be successfully delivered to recipients' inboxes. A high bounce rate is more than just a missed delivery, it is a strong signal to mailbox providers (ISPs) about the quality of your sending practices and the health of your email list.
Understanding what constitutes an acceptable bounce rate threshold and how it directly impacts your sender reputation is fundamental to achieving strong email deliverability. Poor bounce rate management can lead to significant issues, including emails being flagged as spam, throttling, or even your domain and IP addresses being placed on an email blocklist (or blacklist).
Understanding bounce rate thresholds
Generally, an acceptable bounce rate should be below 2-3%. Anything higher than this indicates underlying issues with your email list or sending practices that need immediate attention. While a 0% bounce rate is technically ideal, it is practically impossible due to constant changes in email addresses and mail server statuses.
It's important to distinguish between the two main types of bounces: hard bounces and soft bounces. Hard bounces signify a permanent delivery failure, often due to an invalid or non-existent email address, a blocked recipient, or a domain that does not exist. Soft bounces, on the other hand, indicate a temporary delivery issue, such as a full inbox, a server being temporarily down, or the message size exceeding limits. Understanding their differences is key to effective management.
Hard bounces
These are permanent delivery failures. Examples include invalid email addresses, non-existent domains, or recipient servers that permanently block your mail.
A high hard bounce rate often indicates a poorly maintained list or questionable acquisition practices.
These should be immediately removed from your mailing list to protect your sender reputation.
Soft bounces
These are temporary delivery failures. Common reasons include a full inbox, the recipient server being temporarily unavailable, or the message being too large.
While not as immediately damaging as hard bounces, consistently high soft bounce rates can signal disengagement or issues with recipient servers.
These addresses are often retried over time, but if they continue to soft bounce, they should eventually be removed.
Mailbox providers often consider both the absolute number of bounces and the bounce rate percentage. For example, a small number of bounces from a massive send might be overlooked, but even a few hard bounces from a very small list can quickly flag your sender reputation. While specific thresholds can vary by industry and by the mailbox provider, it is generally understood that a bounce rate exceeding 2% can put your sender reputation at risk. Amazon Pinpoint indicates that a bounce rate of 5% or greater will place an account under review.
Bounce type
Acceptable threshold
Total bounce rate
Generally below 2-3%, ideally below 2%
Hard bounce rate
Ideally below 0.5%, certainly below 2%
Soft bounce rate
Acceptable up to 1-2%, but monitor closely
These thresholds are not rigid rules, but rather strong indicators. Your goal should be to minimize bounces as much as possible, focusing on a clean and engaged list rather than just staying within a numerical limit. The underlying issue causing the bounces is often more important than the exact percentage.
The critical link to sender reputation
High bounce rates directly signal to ISPs (like Google and Yahoo) that you might be sending to an unverified or outdated list. This behavior is often associated with spammers, leading to a damaged sender reputation. Your sender reputation is essentially a trust score that ISPs assign to your sending IP addresses and domains. A good reputation means your emails are more likely to reach the inbox, while a poor one often results in emails landing in spam folders or being rejected outright.
Risks of a poor sender reputation
If your bounce rates consistently exceed acceptable thresholds, ISPs may begin to throttle your email volume, delay delivery, or even outright block your messages. This can also lead to your sending IPs or domains being added to email blocklists (blacklists). High bounce rates can severely impact your deliverability, reducing open and click-through rates, and ultimately undermining the effectiveness of your email campaigns.
Hard bounces are particularly damaging. When an ISP receives a hard bounce from your sending system, it registers that you attempted to send mail to an address that does not exist. Repeated attempts to deliver to such addresses are seen as clear indicators of a negligent or even abusive sender, quickly degrading your sender reputation. This is why immediate and permanent suppression of hard-bounced addresses is crucial.
While soft bounces are less severe individually, a high volume of them can still negatively affect your reputation. Consistent soft bounces might indicate that your recipients are not engaging with your emails or that your email list contains many inactive accounts. ISPs track these signals, and a pattern of high soft bounces can also lead to deliverability issues. Understanding how soft bounces affect deliverability is important for maintaining optimal performance.
Ultimately, ISPs use bounce rates as a key indicator of your list quality and how responsibly you manage your email sending. By keeping bounce rates low, you demonstrate that you are a legitimate sender with a well-maintained, engaged audience, which builds trust and ensures your emails reach the inbox.
Strategies for maintaining healthy deliverability
Maintaining an acceptable bounce rate and protecting your sender reputation requires proactive strategies. The first step is to ensure that your email list acquisition methods are robust and permission-based. Avoid purchasing lists or scraping email addresses, as these practices almost always lead to high bounce rates and significant reputation damage. Instead, focus on building your list organically through opt-in forms.
Key strategies to reduce bounce rates
Regular list cleaning: Routinely remove inactive or unengaged subscribers. This helps reduce soft bounces.
Email validation: Use a service to verify email addresses before sending to them, particularly for new sign-ups. This prevents many hard bounces.
Double opt-in: Require subscribers to confirm their subscription via email. This ensures valid and engaged contacts.
Proper bounce handling: Immediately remove hard bounces from your list. For soft bounces, implement a clear retry policy, and suppress if bounces persist.
Email service providers (ESPs) typically handle hard and soft bounces automatically, but it's essential to understand their specific policies. While hard bounces should lead to immediate removal, soft bounce tolerance can vary. Some ESPs might retry soft-bounced emails multiple times over a period, while others have stricter limits. Be proactive in reviewing these settings and ensuring they align with best practices for deliverability.
Continuous monitoring of your bounce rates is also crucial. Regularly review your email campaign reports to identify any sudden spikes or trends in bounces. Analyzing the bounce reasons can provide valuable insights into potential issues, such as a compromised acquisition source or an aging list. Implementing robust monitoring helps you react quickly to protect your sender reputation and maintain high deliverability.
Views from the trenches
Best practices
Maintain consent-based acquisition: Ensure all subscribers explicitly opt-in to receive your emails, reducing the likelihood of bounces.
Segment and engage: Send relevant content to engaged segments to minimize soft bounces and improve overall list health.
Monitor IP and domain reputation: Track bounce rates at both levels to identify and address specific issues.
Implement feedback loops: Leverage feedback loops to automatically remove addresses that mark your emails as spam.
Common pitfalls
Ignoring soft bounces: While temporary, repeated soft bounces can indicate disengagement and negatively affect sender reputation over time.
Not removing hard bounces promptly: Continuing to send to invalid addresses is a significant red flag for mailbox providers.
Failing to clean inactive subscribers: Old, unengaged contacts are more likely to become bounce addresses or spam traps.
Relying solely on ESPs: Understand your ESP's bounce handling, but take active responsibility for list hygiene.
Expert tips
Combine percentage and volume analysis: Both metrics offer valuable insights, especially for large sending operations.
Focus on the root cause: Investigate why bounces are occurring (e.g., list source, validation process) rather than just reacting to the numbers.
Adapt to mailbox provider definitions: Be aware that different ISPs and ESPs may define hard and soft bounces slightly differently.
Prioritize recipient engagement: A truly healthy list will have low bounces because recipients actively want your emails.
Expert view
Expert from Email Geeks says when considering deliverability, the bounce percentage is generally more critical than the absolute volume, as a high percentage indicates systemic compliance issues with the list, regardless of its size. For example, a 5% bounce rate on a list of 1,000 contacts is as problematic as a 5% bounce rate on a list of 1,000,000, signifying that every 20th contact is problematic and requires immediate attention.
2022-12-02 - Email Geeks
Expert view
Expert from Email Geeks says sending emails to non-existent addresses signals a failure in address collection and removal processes. This indicates that the sending server prioritizes volume over recipient engagement, leading to negative impacts on throughput, potential blocks, and diminished reputation.
2022-12-02 - Email Geeks
Protecting your sending identity
Understanding and managing your email bounce rate is not merely a technical exercise, it is a fundamental aspect of maintaining a healthy and trustworthy sender identity. By adhering to acceptable bounce rate thresholds and actively working to reduce them, you signal to ISPs that you are a responsible sender with a high-quality list. This, in turn, safeguards your sender reputation and ensures your emails reach their intended recipients.
Proactive list hygiene, careful acquisition strategies, and consistent monitoring are the cornerstones of effective bounce rate management. By prioritizing these practices, you not only improve your deliverability but also build stronger relationships with your subscribers, leading to better engagement and overall email marketing success.
