Summary
Email marketers should address permanent bounce errors, such as full or inactive mailboxes, promptly to maintain sender reputation and improve deliverability. The primary recommendation is to immediately remove hard-bouncing addresses from mailing lists, often automating this process. Gmail distinguishes between temporary and permanent full mailbox bounces using different error codes (4.x.x vs. 5.x.x). Before complete removal, some suggest attempting re-engagement based on user actions (login, purchase, click), but this strategy depends on client preferences. Crucial proactive measures include implementing double opt-in, regularly cleaning email lists, authenticating emails (SPF, DKIM, DMARC), monitoring sender scores, and focusing on engagement metrics. Providing website feedback about bounced emails can also enhance user awareness.
Key findings
- Immediate Removal: Hard bounced addresses must be promptly removed to protect sender reputation.
- Gmail Bounce Codes: Gmail uses distinct bounce codes (4.x.x and 5.x.x) to differentiate temporary and permanent full mailbox issues.
- Re-engagement Strategy: Consider re-engagement campaigns contingent on user activity and client strategy.
- Proactive Measures: Double opt-in, email authentication, and list cleaning are essential for preventing bounces.
- Automated Systems: Automate the hard bounce removal process to ensure list hygiene is maintained.
- Engagement Focus: Prioritize engaged users and suppress unengaged users to reduce bounce rates.
- Website Integration: Incorporate bounce information on your website to notify and assist users.
Key considerations
- Gmail Error Interpretation: Understand the nuances of different Gmail bounce codes to handle them appropriately.
- Automated System Accuracy: Ensure your automated bounce management accurately identifies and processes hard bounces.
- Client-Specific Strategy: Adapt your bounce handling strategy based on client guidelines and audience characteristics.
- Comprehensive List Hygiene: Combine hard bounce removal with other list maintenance practices for optimal results.
- Sender Authentication: Implement SPF, DKIM, and DMARC to improve deliverability and reduce the likelihood of bounces.
- Ongoing Monitoring: Monitor engagement levels and suppress unengaged users.
What email marketers say
10 marketer opinions
Email marketers should prioritize handling permanent bounce errors, such as full or inactive mailboxes, to maintain a healthy sender reputation and improve deliverability. The consensus is to promptly remove these addresses from mailing lists, often automating the process. Some suggest attempting re-engagement campaigns before complete removal, depending on the client and specific circumstances. Implementing double opt-in, regularly cleaning email lists, authenticating emails, and monitoring sender scores are also recommended as proactive measures.
Key opinions
- Immediate Removal: Promptly remove addresses that result in hard bounces or permanent failures from your mailing list.
- Automation: Set up automated systems to identify and remove hard bounces from your list efficiently.
- Sender Reputation: Failing to handle permanent bounces can significantly harm your sender reputation, leading to deliverability issues.
- Proactive Measures: Implement double opt-in processes to ensure email address validity from the beginning.
- Re-engagement: Consider re-engagement campaigns for inactive users before permanently removing them, but base this on client and campaign specifics.
- Monitoring: Closely monitor bounce rates to identify and address potential issues with your sending practices.
Key considerations
- Client Strategy: The approach to handling bounces can vary depending on the client and their tolerance for re-engagement strategies.
- Automation Setup: Setting up an automated bounce management system requires careful configuration and monitoring to ensure accuracy.
- Authentication: Implement email authentication protocols (SPF, DKIM, DMARC) to improve deliverability and reduce the likelihood of bounces.
- List Hygiene: Regularly clean your email list to remove not only hard bounces but also inactive or unengaged subscribers.
- Double Opt-in: Consider implementing double opt-in to ensure subscribers want to receive your emails and minimize invalid addresses.
Marketer view
Email marketer from EmailGeek explains that regularly cleaning your email list by removing invalid or inactive addresses is vital for maintaining good sender reputation. This includes promptly removing email addresses that result in hard bounces.
6 Jul 2024 - EmailGeek
Marketer view
Email marketer from Email Geeks shares that they treat accounts over quota for a certain period as abandoned and begin permanent failures. They suggest removing them from general mailings and potentially trying re-engagement after a few weeks, but clarifies the strategy depends on the client.
25 May 2023 - Email Geeks
What the experts say
5 expert opinions
Experts recommend handling permanent bounce errors, such as full or inactive mailboxes, to protect sender reputation. Gmail distinguishes between temporary (4.x.x) and permanent (5.x.x) full mailbox bounces. It's advised to cease sending emails to permanent failures until user re-engagement is evident through logins, purchases, or clicks. Cleaning the email list is critical for reducing bounce rates and improving chances of removal from blocklists. Monitoring engagement metrics and automatically suppressing unengaged users can also minimize permanent bounces. Displaying bounce information on websites can further inform users about email delivery issues.
Key opinions
- Gmail Bounce Codes: Gmail uses different bounce codes (4.x.x vs. 5.x.x) to indicate the nature of mailbox full errors.
- Re-engagement Signals: Wait for re-engagement signals (login, purchase, click) before resuming email sends to previously bounced addresses.
- Website Feedback: Integrate website messaging to inform users about email delivery problems.
- List Cleaning Importance: Cleaning bad addresses from lists is necessary to avoid block listing.
- Engagement Monitoring: Suppressing unengaged addresses reduce bounces.
Key considerations
- Gmail Variations: Be aware of the different types of Gmail bounce messages and what they signify.
- Reputation Impact: Understand the negative impact of sending to permanently failing addresses on your sender reputation.
- Technical Implementation: Implement website feedback mechanisms to alert users to email issues.
- Blocklist Awareness: Identify if on any blocklists.
- Engagement Metrics: Which metrics to check when assessing the level of engagement
Expert view
Expert from Spamresource.com explains that when handling bounces and working to get off a Spamhaus blocklist, it's important to clean the list of bad addresses which will help lower bounce rates, in turn improving reputation and removal from blocklists.
16 Feb 2024 - Spamresource.com
Expert view
Expert from Email Geeks suggests not sending mail to permanent failures until there's a sign of life (login, purchase, click). Otherwise, you are adding a negative tick to your reputation for no reason.
24 Apr 2022 - Email Geeks
What the documentation says
4 technical articles
Email deliverability documentation from Mailjet, SendGrid, Amazon SES, and RFC uniformly advises that email marketers should immediately remove email addresses that generate hard bounces from their mailing lists. Hard bounces, indicated by SMTP 5xx error codes, signify permanent delivery failures (e.g., non-existent email addresses). This practice is crucial for safeguarding sender reputation and ensuring continued deliverability.
Key findings
- Immediate Removal Required: Hard bounced addresses should be immediately removed from mailing lists.
- Permanent Failure Indication: Hard bounces indicate permanent reasons for delivery failure, like non-existent addresses.
- SMTP 5xx Errors: SMTP error codes in the 5xx range signify permanent failures.
- Sender Reputation Impact: Failing to remove hard bounces negatively impacts sender reputation.
Key considerations
- Automated Bounce Processing: Implement automated systems to process bounce notifications and remove hard bounced addresses.
- Distinction Between Hard and Soft Bounces: Ensure your system accurately distinguishes between hard and soft bounces to avoid prematurely removing valid addresses.
- Regular List Maintenance: Combine bounce processing with other list hygiene practices for optimal deliverability.
- Compliance with RFC Standards: Adhere to RFC standards for interpreting SMTP error codes to ensure accurate bounce handling.
Technical article
Documentation from RFC explains that SMTP error codes in the 5xx range indicate permanent failures. Email marketers should interpret these errors as a signal to remove the corresponding email address from their lists.
29 May 2025 - RFC
Technical article
Documentation from Mailjet explains that hard bounces indicate a permanent reason why an email cannot be delivered, such as a non-existent email address. These addresses should be immediately removed from your mailing list to protect your sender reputation.
4 Jun 2024 - Mailjet
Can a hard bounced email address become deliverable again, and under what circumstances?
Do email marketing opt-outs ever expire?
Do soft bounces affect email deliverability and sender reputation?
How are email bounce rates calculated and what is considered a good bounce rate?
How do I troubleshoot email bounce messages?
How do MX records impact email bounces and sender reputation?
