Summary
Across various sources, including marketers, experts, and documentation, a clear consensus emerges regarding email bounce handling: Hard bounces, indicative of permanent delivery failures (nonexistent addresses, blocked domains, 5xx SMTP errors), must be immediately removed from email lists to safeguard sender reputation, avoid spam filters, and ensure optimal deliverability. Soft bounces, representing temporary delivery issues (full inboxes, server problems, 4xx SMTP errors), warrant close monitoring for patterns and persistence. Addresses consistently resulting in soft bounces should eventually be removed as well. Bounce handling policies are generally organisation specific and very subjective depending on many factors.
Key findings
- Hard Bounce = Immediate Removal: Prompt removal of hard bounces is paramount for maintaining a healthy email list and preventing damage to sender reputation.
- Soft Bounce = Monitor & Evaluate: Soft bounces require careful monitoring to detect underlying deliverability issues. Persistently soft bouncing addresses should be removed.
- ESP Reporting: ESPs generally report bounces as 'hard', 'soft', or occasionally 'block', facilitating categorization and appropriate action.
Key considerations
- Impact on Sender Reputation: High bounce rates, particularly hard bounces, serve as a red flag to ISPs, negatively impacting sender reputation and deliverability rates.
- List Hygiene Importance: Regular email list cleaning, with consistent removal of hard bounces, significantly improves engagement metrics and reduces spam placement.
- Pattern Recognition: Monitoring soft bounces for recurring patterns, such as consistent failures from a specific domain, helps pinpoint and resolve broader deliverability challenges.
- Policy Customization: Bounce handling policies are organisation specific and subjective. You should configure this to best suit your organisation.
What email marketers say
10 marketer opinions
The consensus from email marketers and experts is that hard bounces should be immediately removed from email lists to protect sender reputation, avoid spam filters, and maintain deliverability. Soft bounces, indicating temporary issues, should be monitored for patterns and persistence. Consistently soft bouncing addresses should eventually be removed as well. Bounce handling policies are also organization specific, very subjective and depend on many factors, including volume, resource and technical capabilities.
Key opinions
- Hard Bounce Removal: Removing hard bounces is crucial for maintaining a healthy email list and avoiding spam filters. Failure to do so damages sender reputation.
- Soft Bounce Monitoring: Soft bounces should be monitored to identify potential deliverability issues. If a soft bounce persists, removal is necessary.
- Bounce Handling Policy: Bounce handling policies should depend on factors such as volume, resource and technical capabilities. Ensure your policy suits your organisation.
Key considerations
- Sender Reputation: High bounce rates, especially hard bounces, are a red flag to ISPs, negatively impacting sender reputation and deliverability.
- List Hygiene: Regularly cleaning email lists by removing bounces helps improve engagement and reduce the likelihood of emails landing in the spam folder.
- Pattern Identification: Monitoring soft bounces for patterns, such as consistent bounces from a specific domain, can help identify and address broader deliverability issues.
Marketer view
Email marketer from Email on Acid explains that hard bounces negatively impact sender reputation and should be removed instantly. Soft bounces indicate a temporary problem, warranting monitoring, but consistently soft bouncing addresses must also be removed.
24 Sep 2023 - Email on Acid
Marketer view
Marketer from Email Geeks explains that bounce handling policies are organisation specific, very subjective and depend on many factors, including volume, resource and technical capabilities.
15 Dec 2021 - Email Geeks
What the experts say
3 expert opinions
Experts agree that processing bounces, particularly hard bounces, is critical for maintaining email deliverability and a positive sender reputation. Emails typically bounce as 'hard', 'soft', or sometimes 'block'. Handling hard bounces incorrectly, i.e. not removing them from your subscriber lists, can lead to deliverability problems as ISPs track bounce rates as an important metric.
Key opinions
- Bounce Categorization: Bounces are generally classified as hard, soft, or sometimes block bounces by ESPs.
- Hard Bounce Impact: Failing to properly handle hard bounces can lead to deliverability problems as ISPs monitor bounce rates.
- Processing Importance: Processing bounces correctly is essential for preserving deliverability and a positive sender reputation.
Key considerations
- Immediate Unsubscription: Hard bounces should be immediately unsubscribed and suppressed from email lists.
- Limited Retries: Soft bounces may be retried a limited number of times, but should be suppressed if they persist.
- ISP Metrics: ISPs utilize bounce rates as a key metric in determining sender reputation, making proper bounce handling essential.
Expert view
Expert from Email Geeks shares that generally bounces are reported as “hard” “soft” or “block” and that some ESPs don’t use block, they just use soft or hard.
13 Dec 2021 - Email Geeks
Expert view
Expert from Word to the Wise emphasizes the importance of handling hard bounces correctly. Failing to remove hard bounces can lead to deliverability problems as ISPs use bounce rates as a key metric in determining sender reputation.
13 Oct 2021 - Word to the Wise
What the documentation says
4 technical articles
Email deliverability documentation consistently states that hard bounces, indicating permanent delivery failures (e.g., nonexistent address, blocked domain, 5xx SMTP errors), should be immediately removed from mailing lists to maintain a good sender reputation. Soft bounces, indicating temporary issues (e.g., full inbox, server problem, 4xx SMTP errors), can be monitored and retried a few times, but should also be removed if they persist.
Key findings
- Hard Bounce Definition: Hard bounces signify permanent delivery failures due to issues like nonexistent addresses or blocked domains.
- Soft Bounce Definition: Soft bounces signify temporary delivery failures due to issues like full inboxes or server problems.
- Error Code Correlation: 5xx SMTP error codes indicate permanent failures (hard bounces), while 4xx SMTP error codes indicate temporary failures (soft bounces).
Key considerations
- Immediate Removal: Hard bounces should be immediately removed to preserve sender reputation.
- Retries and Monitoring: Soft bounces can be retried and monitored, but persistent soft bounces should also be removed.
- Sender Reputation: Maintaining a clean mailing list by promptly removing hard bounces is crucial for sender reputation.
Technical article
Documentation from RFC defines SMTP error codes. Codes in the 5xx range indicate permanent errors which necessitate removing the email from your list, while 4xx codes indicate transient errors that may be retried.
27 Aug 2024 - RFC
Technical article
Documentation from Mailchimp explains that a hard bounce indicates a permanent reason an email cannot be delivered, such as a nonexistent address or blocked domain. A soft bounce indicates a temporary issue, like a full inbox or server problem. Hard bounces should be immediately removed from your list, while soft bounces can be monitored and retried.
2 Aug 2024 - Mailchimp
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