Summary
When an email hard bounces, a multi-faceted approach is recommended. The immediate technical response is to remove the email from the mailing list to protect sender reputation, aligning with technical standards (5xx SMTP error codes). Analysis of the bounce code can identify the reason (invalid address, blocked domain). Simultaneously, communication with the user is crucial: verify the email address, confirm subscription, and understand their expectations. Additional measures include suppression lists, feedback loops with ISPs, list segmentation, and implementing email authentication (SPF, DKIM, DMARC). Explore if the user can re-subscribe using the 'dot' or 'plus' tricks with Gmail (if your ESP allows). Regularly maintain list hygiene and avoid mailing very old or unknown addresses to prevent hitting spam traps.
Key findings
- Immediate Removal: Hard bounced addresses must be immediately removed from the mailing list.
- Verification is Key: Verifying the recipient's email address and confirming their subscription status is crucial.
- Sender Reputation Impact: Failing to remove hard bounces damages sender reputation.
- Technical Standards: Hard bounces are permanent failures indicated by 5xx SMTP error codes.
- Alternative Addresses: 'Dot' and 'plus' tricks can sometimes bypass hard bounce restrictions (dependent on ESP).
- Catch all implications: If using a catch all account they may think they should be getting a specific email but if it is a hard bounce something is likely wrong at their end that they need to resolve with their email provider.
Key considerations
- Communication Strategy: Establish a protocol for communicating with users who have hard bounced to understand the issue.
- Automated Processes: Automate the removal of hard bounces to maintain list hygiene.
- Authentication Methods: Implement SPF, DKIM, and DMARC to prevent legitimate emails from bouncing.
- List Segmentation: Segment your email list to target engaged users and avoid sending to inactive addresses, reducing bounce rates.
- ESP Handling: Understand how your Email Service Provider handles bounces and implements unsubscribes.
- List Hygiene: Maintain consistent list hygiene practices, including double opt-in, to reduce hard bounces.
What email marketers say
11 marketer opinions
When an email hard bounces, it signifies a permanent delivery failure. The first step is often analyzing the bounce code to determine the cause, ranging from invalid addresses to blocked domains. Immediate action includes removing the address from your mailing list to protect sender reputation, as repeated attempts harm deliverability. Verification steps involve confirming user subscription, checking for typos, and reaching out through alternative channels. Technical solutions include employing suppression lists, feedback loops with ISPs, list segmentation, and implementing email authentication protocols like SPF, DKIM, and DMARC. In some cases, 'dot' or 'plus' tricks with Gmail addresses might bypass suppression if the platform doesn't normalize addresses. Finally, ensure good list hygiene through double opt-in and regular cleansing.
Key opinions
- Immediate Removal: Hard bounced emails should be immediately removed from mailing lists to avoid damaging sender reputation.
- Bounce Code Analysis: Analyzing bounce codes provides insights into the reason for the hard bounce (e.g., invalid address, blocked domain).
- Verification Importance: Confirming user subscription and verifying email address accuracy can resolve issues stemming from typos or unintended subscriptions.
- List Hygiene: Regular list hygiene practices, such as double opt-in and automated unsubscribes, prevent sending to invalid or inactive addresses.
- Alternate Addresses: Dot/plus tricks may allow users to resubscribe with a slight change to the email address.
Key considerations
- Technical Implementation: Implement suppression lists, feedback loops, and email authentication protocols (SPF, DKIM, DMARC) to improve deliverability.
- User Communication: Reach out to users through other channels to verify email addresses and confirm interest.
- Platform Specifics: Understand how your email service provider (e.g., Iterable) handles hard bounces and unsubscribes.
- Segmentation Strategy: Segmenting your list to target engaged users helps avoid sending to inactive addresses.
- Address Validation: Utilizing double opt-in processes will help reduce the number of invalid emails in the future.
Marketer view
Email marketer from Mailjet explains that the first step is to analyze the bounce code provided. This code helps identify the reason for the hard bounce, such as a non-existent email address or a blocked domain. Once the reason is identified, appropriate action can be taken, like correcting the email address or contacting the recipient's email provider.
12 Sep 2023 - Mailjet
Marketer view
Email marketer from HubSpot recommends confirming that the user actually subscribed and intended to receive emails. Additionally, they suggest verifying that the email address was entered correctly, as typos are a common cause of hard bounces. If the user confirms both, further investigation is needed.
19 Jan 2024 - HubSpot
What the experts say
5 expert opinions
When a user's email hard bounces, experts recommend a combination of technical and communicative steps. Verify the accuracy of the email address with the user, checking for typos, and understand their expectations, especially if using a catch-all account. Immediately remove the hard-bounced address from your mailing list to safeguard your sender reputation and avoid further damage from sending to invalid or potentially spam trap addresses. Consider whether a user could create a new address by using the 'dot trick' with Gmail, if your ESP allows it. Overall, prioritize list hygiene and responsible sending practices to maintain good deliverability.
Key opinions
- Address Verification: Confirm the email address and user expectations to identify potential input errors or account issues.
- Immediate Removal: Hard-bounced addresses must be promptly removed to prevent harm to sender reputation.
- Potential Re-engagement: The 'dot trick' can be used to re-engage users if the ESP doesn't normalize email addresses.
- Sender Reputation: Poor list hygiene, like sending to unknown or old addresses, can lead to hitting spam traps and harming your sender reputation.
Key considerations
- User Communication: Direct communication helps understand the user's perspective and identify potential solutions.
- ESP Capabilities: Consider your ESP's handling of email address normalization and its impact on potential 'dot trick' workarounds.
- List Maintenance: Regularly assess your mailing list to avoid sending to inactive addresses and potential spam traps.
- Recipients email provider: If using a catch all account they may think they should be getting a specific email but if it is a hard bounce something is likely wrong at their end that they need to resolve with their email provider.
Expert view
Expert from Spam Resource, John Levine, explains that you should confirm with the recipient the email address they are using and what their expectations are regarding emails they think they should be getting. If they are using a catch all account they may think they should be getting a specific email but if it is a hard bounce something is likely wrong at their end that they need to resolve with their email provider.
20 Dec 2023 - Spam Resource
Expert view
Expert from Email Geeks suggests that the user could use a new email address or ask the recipient to reconfirm their address, checking for typos to ensure the Gmail address is correct and valid.
12 Nov 2022 - Email Geeks
What the documentation says
4 technical articles
Documentation from various sources agrees that the primary action when an email hard bounces is immediate removal from the mailing list. Hard bounces, indicated by a 5xx SMTP error code, represent permanent delivery failures due to reasons such as invalid email addresses, non-existent domains, or blocked delivery. Continuing to send to these addresses negatively impacts sender reputation and deliverability. It's crucial to distinguish hard bounces from soft bounces, which are temporary issues and may warrant retries.
Key findings
- Immediate Removal: Hard-bounced email addresses should be immediately removed from the mailing list.
- Permanent Failure: A hard bounce signifies a permanent delivery failure.
- 5xx Error Code: A 5xx SMTP error code indicates a permanent failure and should not be retried.
- Sender Reputation Impact: Sending to hard-bounced addresses negatively impacts sender reputation and deliverability.
- Distinguish Bounce Types: It's essential to differentiate between hard and soft bounces, as soft bounces may warrant retries.
Key considerations
- Automated Removal: Implement an automated system to remove hard-bounced addresses from your mailing list.
- Bounce Monitoring: Regularly monitor bounce notifications to identify and address deliverability issues.
- List Hygiene: Maintain a clean email list to prevent sending to invalid or non-existent addresses.
Technical article
Documentation from AWS SES explains that the best practice is to immediately remove the email address from your mailing list upon receiving a hard bounce notification. Continuing to send emails to addresses that have hard bounced negatively impacts sender reputation and deliverability rates.
17 Dec 2023 - AWS SES Documentation
Technical article
Documentation from Mailchimp explains that hard bounces happen when an email can't be delivered because the email address is invalid, the domain name doesn't exist, or the recipient's email server has completely blocked delivery. They automatically remove hard bounces immediately to protect sender reputation.
21 Aug 2023 - Mailchimp
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