What bounce rate percentage causes deliverability problems?
Matthew Whittaker
Co-founder & CTO, Suped
Published 28 Jul 2025
Updated 16 Aug 2025
7 min read
Email bounce rate is a critical metric for anyone sending emails, whether for marketing campaigns or transactional messages. It represents the percentage of emails that fail to be delivered to the recipient's inbox and are returned to the sender. A high bounce rate is not just about undelivered messages; it's a significant indicator to internet service providers (ISPs) and mailbox providers that there might be issues with your email sending practices or list hygiene. These issues can severely impact your ability to reach the inbox, affecting your email deliverability and overall sender reputation.
Understanding what constitutes an acceptable bounce rate, and when a percentage becomes problematic, is key to maintaining a healthy email program. While some bounces are inevitable, consistently exceeding certain thresholds can trigger protective measures from mailbox providers, ranging from increased spam filtering to outright blocking of your sending domain or IP address.
Understanding bounce rate thresholds
The generally accepted industry standard for a healthy email bounce rate is typically below 2%. Many experts and platforms recommend keeping your overall bounce rate under this figure to maintain strong deliverability. For example, some sources suggest that a bounce rate below 2% is considered normal and optimal.
Bounce rates between 2% and 5% should be considered a warning sign. While not immediately critical, this range indicates that you should investigate the underlying causes. It might point to a temporary issue, or the beginning of a list hygiene problem that could escalate if left unaddressed. We have an article that delves deeper into what is a good bounce rate percentage to aim for.
When your bounce rate climbs above 5%, it typically enters the critical zone. At this level, many mailbox providers and email service providers (ESPs) will view your sending practices with concern. Platforms like Amazon Pinpoint might pause sending ability if your bounce rate exceeds 5%. Some providers might even disable your registered sender if the bounce rate surpasses this threshold, stopping all further email transmissions. A bounce rate over 10% can even lead to account suspension on most email platforms, as outlined by BigMailer's guidance on bounce rates.
A high bounce rate sends a strong negative signal to ISPs and mailbox providers, significantly harming your sender reputation. When too many emails are sent to invalid or non-existent addresses, it suggests that your list acquisition methods are poor, or that your list is not being regularly cleaned. ISPs interpret this as irresponsible sending, which can lead to your emails being flagged as spam or even blocked entirely. This applies to both your IP address and your domain reputation, making it harder for your legitimate emails to reach the inbox.
The consequences of a damaged sender reputation are far-reaching. You may experience a sharp decline in your inbox placement rates, meaning more of your emails will end up in the spam folder or be rejected outright. This can severely impact the effectiveness of your email marketing efforts and transactional communications. Consistent monitoring of your email deliverability rates is essential to catch these issues early.
Furthermore, a high bounce rate can make you appear on email blocklists (also known as blacklists). These blocklists are databases of IP addresses and domains known for sending unwanted or problematic email. If your domain or IP is listed on a major blacklist, it can prevent your emails from reaching a wide range of recipients. Understanding what happens when your domain is on an email blacklist is crucial for proactive management. This is why blocklist monitoring is a key part of email security.
Persistent high bounce rates lead to blocklists
Sustained high bounce rates, especially from hard bounces, are a major red flag for mailbox providers and can quickly lead to your IP or domain being added to internal or public blocklists (or blacklists). This can result in widespread email delivery failures, severely impacting your communication efforts. Regularly checking your email deliverability health is essential.
Types of bounces and their severity
Not all bounces are created equal. There are two primary types: hard bounces and soft bounces, each with different implications for your deliverability and sender reputation. Hard bounces indicate a permanent delivery failure. This typically means the email address does not exist, the domain name is invalid, or the recipient's server has permanently blocked your address. Hard bounces are the most damaging to your sender reputation, and these addresses should be immediately removed from your mailing list to prevent further issues.
Soft bounces, on the other hand, indicate a temporary delivery issue. This could be due to a full inbox, an overloaded server, or the recipient's server being temporarily down. While a single soft bounce isn't as critical as a hard bounce, a pattern of repeated soft bounces to the same address signals a problem. Mailbox providers will often attempt to redeliver soft bounced emails, but if they continue to fail, they can eventually be treated like hard bounces and negatively impact your reputation. You should understand what is a reasonable soft bounce tolerance for your campaigns.
Hard bounces
Hard bounces are permanent failures. They occur when an email address is invalid, nonexistent, or has been permanently blocked by the recipient's server. They significantly harm your sender reputation.
Impact: Direct and severe negative impact on sender reputation. Leads to poor inbox placement and potential blocklisting.
Action: Immediately remove these addresses from your list. Do not attempt to send to them again. Regularly clean your email list.
Soft bounces
Soft bounces are temporary delivery failures. Causes include a full inbox, server downtime, or a message too large. Mailbox providers may retry delivery.
Impact: Less severe initially, but repeated soft bounces to the same address can be interpreted negatively and harm reputation over time.
Action: Monitor patterns. If an address consistently soft bounces, consider removing it or re-engaging the subscriber. Address underlying issues like email size or sending frequency.
Strategies for minimizing bounce rates
To keep your bounce rate in check and protect your deliverability, proactive list hygiene is paramount. This means regularly cleaning your email list to remove invalid or inactive addresses. Employing a double opt-in process for new subscribers can significantly reduce initial bounce rates by ensuring that only genuinely interested and valid email addresses are added to your list. It confirms that the email address belongs to the subscriber and they actively wish to receive your communications.
Additionally, consider implementing email verification at the point of signup, such as CAPTCHAs or other bot detection techniques. While some argue this might affect conversion rates, it filters out bogus emails that would otherwise become hard bounces. There's a debate on the effectiveness of third-party verification services versus improving acquisition methods. Some senders find email verification critical for data quality, while others prefer stronger opt-in processes.
Beyond initial acquisition, ongoing list management is crucial. Segment your audience and tailor content to ensure relevance, which can help prevent inactive accounts from becoming bounce traps or spam traps. Regularly re-engage inactive subscribers, and if they don't respond, consider removing them. This practice helps maintain a healthy sending environment and improves overall email deliverability rates.
Example: identifying bounced emails in logs (conceptual)Text
550 5.1.1 <user@example.com>: Recipient address rejected: User unknown in local recipient table
550 5.2.1 <user@example.com>: Mailbox unavailable or access denied
451 4.2.2 <user@example.com>: Recipient's mailbox is full
554 5.7.1 <user@example.com>: Service unavailable; Client host [192.0.2.1] blocked using Spamhaus
Views from the trenches
Best practices
Maintain bounce rates over time, especially by domain, to identify issues.
Implement strong subscriber acquisition methods like CAPTCHAs and confirmed opt-in to reduce bad sign-ups.
Regularly clean your email lists to remove invalid addresses and mitigate long-term deliverability problems.
Understand the lifetime value of an email subscriber to quantify the financial impact of deliverability issues.
Common pitfalls
Not caring about bounces, as they represent non-buying addresses and lost revenue.
Focusing solely on conversion rates at the expense of email list quality.
Assuming all email verification services are effective; some may be a waste of resources.
Ignoring the long-term impact of high bounce rates on sender reputation and inbox placement.
Expert tips
A bounce rate above 2% should raise red flags for list hygiene or sender reputation.
While a 0% bounce rate is impossible, striving for the lowest possible rate is always the goal.
Consider the unquantifiable efforts in deliverability, as even small improvements can lead to significant long-term income.
Don't overlook spam traps, which don't bounce but severely impact deliverability.
Expert view
Expert from Email Geeks says bounces are not converting into sales and likely cost money, making it poor business practice to disregard them. They also noted that while spam traps are a greater concern because they don't bounce, certain bounce reasons and mailbox providers can definitely cause deliverability problems, leading to spam folder placement or outright blocking. Quantifying specific thresholds is challenging due to variable factors.
December 13, 2022 - Email Geeks
Expert view
Expert from Email Geeks advises senders to adopt as many industry best practices as possible for deliverability. They acknowledged that achieving 100% inbox placement is impossible, with some emails always going to spam. However, they emphasized that even a small improvement, like going from 93% to 95% inbox placement, is beneficial for a marketer and can lead to solid income over the years, despite not seeming significant in the short term.
December 13, 2022 - Email Geeks
Sustaining a healthy sending reputation
Ultimately, managing your bounce rate is a continuous effort that is integral to sustaining a healthy sender reputation. It's not just about hitting a specific low percentage, but about understanding the types of bounces you receive, their underlying causes, and consistently adapting your practices. Regular monitoring of your email deliverability metrics, including bounce rates, is paramount. This enables you to proactively address issues before they escalate into significant deliverability problems, keeping your emails out of the spam folder and in the inbox.
Think of your bounce rate as a barometer for the health of your email list and sending infrastructure. By keeping it as low as possible, ideally below 2%, you signal to ISPs that you are a responsible sender. This proactive approach ensures your messages consistently reach their intended recipients, maximizing the impact of your email communications.
