What is a reasonable soft bounce tolerance in email marketing?
Matthew Whittaker
Co-founder & CTO, Suped
Published 23 May 2025
Updated 19 Aug 2025
9 min read
Understanding what constitutes a reasonable soft bounce tolerance in email marketing is crucial for maintaining strong deliverability and a healthy sender reputation. Unlike hard bounces, which indicate permanent delivery failures, soft bounces are temporary issues. However, if left unaddressed or if the volume is too high, repeated soft bounces can still signal problems to internet service providers (ISPs) and affect your ability to reach the inbox. It is important to know when to stop attempting delivery to an address that consistently soft bounces.
The key is to define a threshold at which these temporary issues are no longer considered temporary and instead warrant suppression to protect your sending domain. This threshold, or tolerance, needs to be carefully calibrated to balance reaching as many engaged subscribers as possible against avoiding actions that could lead to being blocklisted (or blacklisted) or having your emails routed to the spam folder.
Understanding soft bounces and their impact
Soft bounces occur for several reasons, such as a recipient's mailbox being full, the server being temporarily unavailable, or the message size exceeding the recipient's limit. These are not permanent errors, meaning the email address itself is valid. An email classified as a soft bounce in one sender's campaign can often be delivered normally in another sender's campaign, or even successfully delivered at a later time by the same sender once the temporary issue is resolved. However, ignoring repeated soft bounces can be detrimental.
ISPs monitor sending behavior closely. A high volume of soft bounces, especially if they are persistent for certain addresses, can be interpreted as a sign of poor list hygiene or aggressive sending practices. This can lead to a damaged sender reputation, causing your emails to be marked as spam or even triggering a blocklist (or blacklist) placement. It is crucial to understand that even temporary failures impact your overall email deliverability. To learn more about how soft bounces affect your reputation, you can review details on if soft bounces affect deliverability.
Different email service providers (ESPs) and mailbox providers have their own ways of classifying and handling soft bounces. Some might retry delivery for a set period, while others might classify an address as a soft bounce after a single attempt, waiting for future campaigns to retry. The key distinction to remember, as highlighted by HubSpot's explanation, is that a soft bounce signals a temporary problem, while a hard bounce indicates a permanent one.
ESPs typically employ various strategies to manage these bounces. Many providers like Mailchimp automatically suppress addresses after a certain number of consecutive soft bounces. This proactive approach helps protect their shared IP reputation, which in turn benefits all senders using their platform. Understanding your ESP's specific soft bounce handling is a vital part of your deliverability strategy. More on this topic can be found in our article on how ESPs manage bounces.
Determining a reasonable soft bounce tolerance
There isn't a universally agreed-upon reasonable soft bounce tolerance that applies to all email marketing campaigns. Many factors influence what is considered acceptable, including your sending volume, list quality, content, and the specific ISPs you are sending to. However, general industry recommendations for overall bounce rates suggest keeping it below 2%. For instance, AgencyAnalytics recommends a soft bounce rate below 2% as a good indicator.
When it comes to individual addresses, many ESPs often use a threshold of 5 to 7 consecutive soft bounces before automatically suppressing an email address. This means if an email to a particular address soft bounces 5 to 7 times in a row, it's typically removed from active sending. This number accounts for the temporary nature of soft bounces while also recognizing that persistent issues suggest a need for suppression. For more information, read our article how many soft bounces before suppressing a user.
The critical dimension here is consecutive bounces, rather than a lifetime count. If an address soft bounces once, then successfully receives emails for months, and then soft bounces again, these instances are typically not counted towards a consecutive limit. The focus is on a string of failures that indicates a persistent problem with that specific mailbox. This differs from a soft bounce suppression logic that considers the overall history.
This table outlines common soft bounce scenarios and recommended actions:
Soft Bounce Scenario
Typical Response
Recommended Action
Mailbox full
Retry delivery for a few attempts.
Suppress after 3-5 consecutive bounces; re-engage later if possible.
Server temporarily unavailable
Retry for up to 72 hours.
Monitor for consistent issues across multiple recipients for that domain.
Message too large
Will typically soft bounce immediately.
Review content and size; suppress if recurring.
Implementing and managing soft bounce suppression
The automatic suppression logic of ESPs is often a good baseline, but active management by marketers is still essential. This involves regularly monitoring your bounce rates, segmenting your lists based on engagement, and proactively cleaning your email database. Ignoring soft bounces can lead to a gradual decay in your sender reputation and increased spam folder placement. You can learn more about how to suppress soft bounces for better list hygiene.
It is also crucial to distinguish between a soft bounce tolerance and an email retry interval. Soft bounce tolerance refers to how many times you will allow an email address to soft bounce consecutively before suppressing it. This typically applies to separate sending attempts over time. A retry interval, on the other hand, is the period an ESP will attempt to resend a single email that initially soft bounced within a short timeframe, usually hours or a few days. Confusing these two can lead to over-sending or premature suppression.
For ongoing campaigns, regularly reviewing your soft bounce data allows you to identify patterns. Are soft bounces concentrated on specific domains? Are they increasing after a certain type of campaign? These insights can help you adjust your sending frequency, content, or list segmentation strategies. For example, if you see an increase in soft bounces after a sudden email volume spike, there are ways to reduce those soft bounces.
Best practices for soft bounce management
Timely Suppression: Suppress email addresses after 5-7 consecutive soft bounces. This prevents further negative impact on your sender reputation.
Segment Engaged Users: Focus sends to actively engaged segments to reduce overall bounce rates.
Monitor Bounce Categories: Pay attention to specific soft bounce codes to identify recurring issues.
Strategies to minimize soft bounces and protect sender reputation
Proactive measures are always better than reactive fixes. Regular email list hygiene, including email validation services, can significantly reduce the number of soft bounces you encounter. While validation primarily targets hard bounces and invalid addresses, a clean list generally leads to better engagement and fewer temporary issues overall. Understanding typical bounce rates after email validation can help set realistic expectations.
Ensuring your email authentication protocols are correctly configured is another fundamental step. SPF, DKIM, and DMARC help verify that your emails are legitimate, which can indirectly reduce soft bounces by improving your overall sender reputation and reducing the likelihood of mailbox providers treating your emails with suspicion. A strong sender reputation means mailbox providers are more likely to accept your mail, even if a recipient's inbox is temporarily full, rather than just rejecting it outright. You can find more information about this in our guide to boosting deliverability rates.
Sender reputation is built over time through consistent good sending practices. High soft bounce rates, especially if consistent, can indicate issues that may lead to blocklisting. Maintaining an acceptable bounce rate, generally below 2% as noted by industry sources, is critical. If your bounce rates climb above this, it's a strong signal to investigate and adjust your strategy to avoid being flagged as a risky sender. This is also covered in our article what is a good bounce rate percentage.
Common pitfalls
Ignoring soft bounce patterns: Failing to analyze why and where soft bounces occur can prevent effective strategy adjustments. This can lead to persistent deliverability issues and lower inbox placement rates.
Over-reliance on ESP auto-suppression: While helpful, ESPs' default settings might not always align perfectly with your specific sending needs or audience behavior. Blindly trusting defaults can be risky.
Infrequent list cleaning: Delaying the removal of consistently bouncing addresses allows reputation damage to accumulate. Stale lists are prone to higher bounce rates, both hard and soft.
Effective strategies
Custom suppression rules: Implement rules that consider consecutive bounces over a specific timeframe, rather than just a total count. This allows flexibility for temporary issues.
Engagement-based re-engagement: For addresses that occasionally soft bounce but show engagement, consider re-engaging them with a targeted campaign before full suppression.
Domain-specific adjustments: If certain domains consistently generate soft bounces, investigate potential issues, such as specific DMARC policies or greylisting rules from those domains.
Views from the trenches
Best practices
Actively monitor soft bounce rates and categorize them by reason to identify underlying patterns and root causes. This detailed insight helps in addressing specific deliverability challenges.
Implement a clear, consistent suppression policy for addresses that repeatedly soft bounce, typically after 5-7 consecutive failures, regardless of the ESP's default settings. This proactive approach safeguards sender reputation.
Regularly segment your email lists based on engagement levels, sending more frequently to active subscribers and less often to those with low engagement or recent soft bounces. This optimizes resource use and improves inbox placement.
Common pitfalls
Failing to differentiate between temporary soft bounce issues and persistent problems, leading to either premature suppression of valid contacts or prolonged sending to problematic addresses.
Relying solely on your ESP's default soft bounce handling, which may not be aggressive enough to prevent reputation damage, especially for high-volume senders or those with varied list quality.
Ignoring the cumulative effect of soft bounces on overall sender reputation, which can gradually lead to lower inbox placement, increased spam folder delivery, or even IP/domain blocklisting (or blacklisting).
Expert tips
Consider a re-engagement campaign for contacts who soft bounce due to a full mailbox; they might still be interested but just need a break or a different communication channel.
For large sending volumes, integrate bounce data with your CRM or marketing automation platform to automate suppression and segment management.
Analyze domain-specific soft bounce rates. If a particular domain frequently generates soft bounces, it might indicate unique handling policies at that mailbox provider, requiring tailored strategies.
Expert view
Expert from Email Geeks says Klaviyo, the email service provider my company uses, has a policy that allows up to 7 consecutive soft bounces before suppressing an email address.
2019-05-31 - Email Geeks
Expert view
Expert from Email Geeks says a soft bounce tolerance of 7 consecutive bounces sounds reasonable.
2019-05-31 - Email Geeks
Maintaining email list health
Ultimately, defining a reasonable soft bounce tolerance is a dynamic process that requires continuous monitoring and adjustment. There is no one-size-fits-all number, but understanding the nature of soft bounces, adhering to industry best practices, and actively managing your email lists are paramount.
By striking the right balance between retrying temporary failures and promptly suppressing persistently problematic addresses, you can safeguard your sender reputation, ensure high deliverability rates, and maximize the effectiveness of your email marketing efforts. Focusing on good email list hygiene and being proactive about bounce management will always yield the best long-term results.
