Summary
Determining the optimal number of soft bounces before suppressing a user is a nuanced decision in email deliverability. Soft bounces typically indicate temporary delivery issues, such as a full mailbox or a mail server being temporarily unavailable. While these issues might resolve themselves, allowing an address to soft bounce indefinitely can harm your sender reputation and inflate your mailing list with unengaged or unmailable contacts. There is no universally agreed-upon threshold, as the ideal number depends heavily on your sending frequency, the specific type of soft bounce, and your overall deliverability strategy. Many email service providers (ESPs) have their own internal policies, but marketers often seek to implement more tailored approaches based on their unique circumstances. Understanding the distinction between hard and soft bounces is fundamental.
Key findings
- No universal standard: ESPs employ varying thresholds, from 3 to 15 consecutive soft bounces, before deeming an address undeliverable or hard bouncing.
- Temporary vs. permanent: Soft bounces are transient, but repeated soft bounces often signify an underlying, persistent problem that warrants eventual suppression.
- Impact on sender reputation: Continuously sending to soft-bouncing addresses can negatively affect your sender reputation and inbox placement.
- ESP limitations: Some ESPs offer general soft bounce filters without granular control over specific bounce types.
Key considerations
- Define soft bounces: Understand how your ESP categorizes different bounce types. For more on this, read our article what is the difference between hard and soft email bounces.
- Sending frequency: A higher sending frequency might warrant a lower soft bounce threshold, while monthly sends could tolerate more.
- Risk tolerance: Aggressive suppression can remove deliverable users, but a lax policy risks poor deliverability and potential blocklisting (also known as blacklisting). Learn more about email blocklists.
- Data analysis: Analyze your bounce data to identify patterns, such as how many soft bounces typically resolve for your specific audience. Understanding bounced emails is key.
- ESPs' approach: Klaviyo, for instance, suppresses profiles after seven consecutive soft bounces. Others, like MailChimp, have similar automatic thresholds.
What email marketers say
Email marketers often face a dilemma: balance maintaining a large contact list (driven by internal pressure) with optimizing deliverability by suppressing unengageable contacts. While ESPs offer features for soft bounce management, marketers desire more automated and nuanced solutions to avoid manually cleaning lists or risking valuable subscribers. There's a shared sentiment that a more proactive approach from ESPs would greatly simplify bounce handling and improve overall list hygiene.
Key opinions
- Desire for automation: Many marketers wish ESPs would automatically clear soft-bouncing addresses after a set number of failures.
- Risk of over-suppression: Concerns exist about suppressing valid recipients who might resolve temporary issues, especially with generic soft bounce filters.
- Balancing list size and engagement: Leadership pressure to maintain large list sizes often conflicts with deliverability best practices. Cleaning up soft bounces is crucial for sender reputation, as discussed in our article cleaning up soft bounces.
- Varied sending patterns: A universal suppression rule is difficult due to diverse sending frequencies across brands (daily vs. weekly/monthly).
Key considerations
- Understand ESP filters: If a soft bounce filter is general, it combines various temporary issues like 'mailbox full' or 'domain unreachable', making granular management difficult. For more insights into how ESPs manage bounces, refer to how email service providers manage bounces.
- Internal resistance: Product teams may resist changes to long-standing suppression systems due to user experience implications.
- Monitoring SMTP responses: Be cautious interpreting generic 'soft bounce' labels; some SMTP responses might indicate temporary sender IP issues, not recipient problems.
- Proactive hygiene: Beyond bounce management, implementing double opt-in and sending only to engaged users can naturally reduce dormant and soft-bouncing recipients. This helps in preventing and resolving high bounce rates.
Marketer view
Marketer from Email Geeks suggests that a general soft bounce filter, encompassing issues like mailbox full or domain unreachable, makes it challenging for marketers without technical expertise to effectively utilize. It would be easier if the ESP handled these complexities automatically.
Marketer view
Marketer from Email Geeks indicates that their product team often resists lowering the soft bounce suppression threshold because of user experience concerns and the varied sending frequencies of different brands. Finding a healthy balance across all brands is a significant challenge.
What the experts say
Email deliverability experts agree that the definition and handling of soft bounces are often inconsistent across platforms, making a universal suppression rule difficult. While some soft bounces are truly temporary, many effectively become permanent failures if an ESP exhausts its retry attempts. Experts advise that relying solely on a generic 'soft bounce' label can be misleading. A more sophisticated approach involves analyzing specific SMTP responses, considering the sending frequency, and implementing a time-based suppression policy to preserve sender reputation without prematurely removing potentially valid recipients.
Key opinions
- Soft bounces often become hard: What appears as a soft bounce in an ESP interface might actually be a permanent failure after internal retries are exhausted.
- Context is key: The ideal soft bounce threshold depends on factors like sending frequency; 7 bounces daily is different from 7 monthly.
- No perfect number: There's no single perfect number of soft bounces before suppression due to disparate sender practices and risk tolerances.
- Nuance in definition: Soft bounces are loosely defined, typically as temporary rejections or deferrals expected to resolve themselves. However, this definition can be misleading.
Key considerations
- Analyze SMTP responses: Focus on the underlying SMTP response codes (e.g., 4xx for temporary, 5xx for permanent) to understand the true nature of a bounce. Our guide on which SMTP bounce codes lead to mailing list suppression provides more detail.
- Implement time-based suppression: Consider suppressing after a certain number of consecutive 5xx errors over a defined period (e.g., 3 bounces over 15 days). This is part of a robust recommended soft bounce suppression logic.
- Avoid premature suppression: Be cautious about aggressively suppressing soft bounces, as it might remove engaged recipients who merely experienced a temporary issue. This balances risk with engagement.
- Sender practices matter: The overall effectiveness of soft bounce management is tied to consistent sender practices and risk tolerance. Learn more about email marketing red flags related to high bounces in this SocketLabs article.
Expert view
Expert from Email Geeks explains that many ESPs define an address as 'hard bouncing' after a specific number of consecutive soft bounces, for instance, 15 or 7 if there is no prior history. This conversion helps streamline internal bounce handling.
Expert view
Deliverability expert from SpamResource.com states that while soft bounces are typically temporary, consistent soft bounces indicate an underlying issue that warrants suppression for list hygiene. Ignoring them can harm sender reputation.
What the documentation says
Official documentation from various email service providers and marketing platforms reveals diverse approaches to soft bounce suppression. While they all aim to protect sender reputation and optimize deliverability, their specific thresholds and methodologies vary significantly. Some provide hard numbers for consecutive soft bounces before suppression, while others emphasize the need for marketers to monitor patterns and make informed decisions, sometimes in consultation with deliverability experts. These guidelines highlight that while soft bounces are generally temporary, a recurring pattern signals a need for action to maintain list hygiene and ensure efficient email delivery.
Key findings
- Varied suppression defaults: ESPs like Brevo (4), Salesforce (5), and Klaviyo (7) have different default numbers for consecutive soft bounces leading to suppression.
- Manual suppression option: Some platforms allow list owners to manually suppress contacts, providing flexibility beyond automated rules.
- Consecutive counts: Emphasis is often placed on consecutive soft bounces rather than cumulative counts over time.
- Impact of sending frequency: Recommended acceptable soft bounce rates differ significantly based on sending frequency (e.g., daily vs. monthly campaigns).
Key considerations
- ESPs define soft bounces: The way an ESP classifies a 'soft bounce' (e.g., rejection vs. deferral) impacts its internal suppression logic. Understanding ESP definitions helps to set a reasonable soft bounce tolerance.
- Consult experts: If standard defaults don't align with observed bounce patterns, documentation often advises consulting a deliverability expert.
- Internal retry policies: Be aware that ESPs typically attempt retries for soft bounces for a period (e.g., 72 hours) before reporting them as permanent failures. These retry policies significantly affect domain reputation and deliverability.
- Protect deliverability: Documentation consistently emphasizes that reducing sending to recipients with sustained soft bounces is crucial for maintaining optimal email deliverability and avoiding blocklists (blacklists). Mailgun outlines what to do about email bounces.
Technical article
Klaviyo documentation states that a profile is suppressed due to 7 consecutive soft bounces or a single hard bounce, and will be automatically removed from associated lists. This automated process aids in maintaining list hygiene.
Technical article
AtData's partner insights recommend a general rule of thumb for soft bounces, suggesting that 6 consecutive soft bounces should lead to the removal of the record from the mailing file. This proactive measure prevents repeated attempts to unmailable addresses.
Related resources
12 resources
Related pages
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What is the recommended soft bounce suppression logic for email?
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Why Your Emails Fail: Expert Guide to Improve Email Deliverability
