Summary
The recommended soft bounce suppression logic varies among experts, but a consistent theme is the establishment of thresholds for repeated failures. While Email Service Providers often manage initial retries for temporary delivery issues, marketers are widely advised to implement their own strategies for addresses that exhibit chronic soft bouncing. The general consensus suggests suppressing an email address after a certain number of consecutive soft bounces or following a defined period of persistent temporary delivery failures, which is crucial for protecting sender reputation and maintaining a clean, effective email list.
Key findings
- Common Thresholds: Many experts suggest suppressing an email address after 3-5 consecutive soft bounces, though recommendations vary, with some sources mentioning as few as 2 or as many as 7 bounces.
- Time-Based Logic: Often coupled with bounce counts, a time component is advised. This can range from a few days, typically 2-5, to several weeks, indicating a chronic rather than a brief delivery issue.
- ESP vs. Sender Roles: While Email Service Providers like Mailchimp and SendGrid handle initial retries for soft bounces, the ultimate responsibility for suppressing an address after repeated temporary failures rests with the sender to protect their list health.
- Impact on Reputation: Continuously attempting delivery to addresses that consistently soft bounce can negatively affect sender reputation and overall deliverability, despite the temporary nature of individual bounces.
- Conversion to Hard Bounce: Some ESPs, such as Mailchimp, automatically convert an address into a hard bounce and remove it from the list after a specific number of soft bounces, for example, five across multiple campaigns.
Key considerations
- Define Persistence: Marketers must establish clear internal criteria for what constitutes a persistent soft bounce, balancing the potential for future successful delivery with the critical need for robust list hygiene.
- Monitor and Analyze: Consistent monitoring of soft bounce rates and the behavior of individual email addresses is essential to identify recurring issues and determine when suppression is necessary.
- Reputation Protection: Proactively suppressing addresses that repeatedly soft bounce is a key strategy for safeguarding and enhancing sender reputation, preventing wasted sending efforts.
- Bounce Reason Nuances: It is important to understand that not all temporary delivery failures are equal; some, like a full mailbox, may count towards suppression, while others, such as spam classification rejections, might not.
What email marketers say
15 marketer opinions
To maintain strong sender reputation and ensure list quality, marketers must implement a clear strategy for managing soft bounces beyond initial automated retries. Although these bounces are temporary, persistent occurrences signal a chronic issue. Experts broadly agree on establishing specific thresholds, combining a count of consecutive soft bounces with a defined timeframe, before permanently suppressing an email address from active sending.
Key opinions
- Variable Thresholds: Specific recommendations for soft bounce suppression range from 2 to 7 bounces, with 3-5 being a frequently cited range, often applied consecutively.
- Time-Based Component: Many strategies incorporate a time element, advising suppression if soft bounces persist over periods ranging from a few days, such as 2-5 days, to several weeks, or even a month, across multiple campaigns.
- Consecutive vs. Total Bounces: Some recommendations specifically highlight consecutive soft bounces as the trigger, while others refer to a total count over time, indicating a more chronic issue.
- Selective Counting of Bounces: Not all temporary delivery failures are treated equally; for example, rejections due to spam classification may not count towards suppression thresholds, unlike a 'mailbox full' status.
- Reclassifying Persistent Issues: An address that consistently soft bounces over a prolonged period is often treated similarly to a hard bounce, leading to its removal from the active sending list to prevent ongoing deliverability problems.
Key considerations
- Defining Persistence: Marketers should proactively establish specific internal rules to define what constitutes a persistent soft bounce, moving beyond the technical definition of temporary.
- Strategic Monitoring: Continuous monitoring of individual contact bounce behavior and overall soft bounce rates is crucial for identifying patterns that necessitate suppression.
- Protecting Sender Reputation: Aggressively managing persistent soft bounces is vital for safeguarding sender reputation and avoiding negative impacts on overall email deliverability.
- List Hygiene Benefits: Implementing robust soft bounce suppression contributes significantly to maintaining a clean, engaged email list, reducing wasted sending efforts.
- Re-engagement vs. Suppression: For some persistently bouncing addresses, an alternative approach might be to move them to a re-engagement list for a later, targeted attempt rather than immediate, permanent suppression.
Marketer view
Marketer from Email Geeks shares that 3 bounces over at least 2 weeks has been a common guideline and notes that M3AAWG suggests at least 2 bounces over at least two weeks.
21 Feb 2023 - Email Geeks
Marketer view
Marketer from Email Geeks recommends removing an address after no more than 5 soft bounces total, and advises sending to hard bounces only once to avoid reputation damage.
5 Dec 2021 - Email Geeks
What the experts say
2 expert opinions
For managing soft bounces, industry experts advocate for a brief, defined retry period before an email address is moved to a suppression list. The common guidance involves reattempting delivery a limited number of times, typically 2 to 5 attempts, over a short span of 2 to 5 days. If an address continues to soft bounce after these initial retries, it should then be treated as a permanent failure, necessitating its removal from active mailing lists to protect sender reputation and optimize list hygiene.
Key opinions
- Recommended Retry Attempts: Experts suggest reattempting delivery for soft-bounced emails a limited number of times, typically ranging from 2 to 5 attempts.
- Timeframe for Retries: These retries are generally advised to occur over a brief period, with common recommendations spanning 2 to 5 days.
- Conversion to Hard Bounce: If an email address continues to soft bounce after the specified retries or time limit, it should then be reclassified as a hard bounce, signaling a permanent delivery failure.
- Mandatory List Removal: Addresses that consistently fail to deliver after the retry period should be removed from the active mailing list to prevent further negative impact on sender reputation.
- Preference for Day Limits: Some specialists advocate for setting time-based limits, such as a number of days, rather than just attempt counts, for determining when to suppress an address.
Key considerations
- Establish Clear Retry Logic: Marketers must precisely define the number of retry attempts and the timeframe over which soft bounces will be reattempted before an address is flagged for suppression.
- Automated Suppression: Implementing an automated system that transitions persistently soft bouncing addresses to a hard bounce status and removes them from active lists is crucial for efficiency and list health.
- Impact on Deliverability: Failing to properly manage and suppress addresses that consistently soft bounce can negatively affect a sender's reputation and overall email deliverability.
- Proactive List Cleaning: Regularly removing contacts that convert from temporary soft bounces to persistent failures is essential for maintaining a clean, high-performing email list.
Expert view
Expert from Spam Resource explains that for soft bounces, it's recommended to retry sending the email a few times, typically 2-3 times over 2-3 days. If the emails still fail after these retries, then the address should be treated as a hard bounce and further sending should cease.
30 Nov 2022 - Spam Resource
Expert view
Expert from Word to the Wise explains that for transient (soft) bounces, standard practice recommends retrying the message for 3 to 5 days or 3 to 5 attempts. She prefers day limits, after which the address should be marked as bad and removed from the active mailing list if it continues to bounce.
9 Jul 2024 - Word to the Wise
What the documentation says
4 technical articles
The consensus among leading email service providers and experts is that while most ESPs handle initial, temporary retries for soft bounces, the sender bears the ultimate responsibility for implementing a robust long-term suppression strategy. This involves actively monitoring bounce patterns and establishing specific criteria, such as a set number of repeat soft bounces over a defined period, to determine when an email address should be removed from active sending lists to protect deliverability and sender reputation.
Key findings
- ESP Automatic Retries: Leading ESPs like Mailchimp, AWS SES, Postmark, and SendGrid automatically attempt to re-deliver emails that initially soft bounce, typically for a short duration or a few attempts.
- Sender's Long-Term Responsibility: Despite initial ESP retries, senders are advised to define and enforce their own soft bounce suppression rules for addresses exhibiting persistent temporary failures.
- Defined Bounce Thresholds: Some ESPs, like Mailchimp, have clear internal rules, for example, five soft bounces across campaigns leading to hard bounce conversion, while others expect senders to define their own thresholds.
- Time-Based Persistence: Repeated soft bounces over an extended duration, such as several weeks or months, or across multiple campaigns, are key indicators that an address should be suppressed.
- Reputation Protection & List Hygiene: The primary drivers for proactive soft bounce suppression by senders are safeguarding sender reputation and ensuring the overall health and effectiveness of their email lists.
Key considerations
- Establish Clear Suppression Logic: Marketers should define precise criteria for persistent soft bounces, including the number of failures and the timeframe over which they occur, before an address is suppressed.
- Consistent Monitoring: Regular review of bounce notifications and individual email address performance is critical for identifying patterns of persistent soft bounces that require action.
- Proactive List Management: Implementing a system to automatically or manually remove addresses that meet the defined soft bounce suppression criteria is essential for maintaining a clean and high-performing list.
- Sender Reputation Impact: Neglecting to manage addresses that continually soft bounce can severely impact sender reputation, leading to poorer deliverability across all campaigns.
Technical article
Documentation from Mailchimp Support explains that soft bounces are temporary delivery issues. Mailchimp automatically retries sending these emails, and if an email address soft bounces five times across five different campaigns, it is converted into a hard bounce and cleaned from the audience list.
8 Sep 2021 - Mailchimp Support
Technical article
Documentation from AWS Simple Email Service (SES) Documentation explains that while SES handles retries for temporary soft bounces, it is ultimately up to the sender to decide when to stop sending to an address that repeatedly soft bounces. They recommend closely monitoring bounce notifications and maintaining a suppression list for addresses showing persistent temporary failures, suggesting removal after a certain number of attempts or a defined time period.
5 Feb 2024 - AWS Simple Email Service (SES) Documentation
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