Is it bad to email addresses that keep soft bouncing?

Key findings

• Reputation Risk: Persistent soft bounces can negatively impact your sender reputation, making ISPs less likely to deliver your emails to the inbox, even for valid recipients.
• Spam Trap Potential: Mailboxes that consistently soft bounce due to abandonment might eventually be converted into spam traps, which can severely damage your domain's sending ability if hit.
• Resource Drain: Continuously sending to undeliverable addresses wastes your ESP's (and your own) resources and can incur unnecessary costs.
• ISP Policies: Many ISPs and email service providers have internal policies that will eventually stop accepting mail for addresses that soft bounce too many times, effectively treating them as hard bounces over time.

Key considerations

• Implement Suppression: Even if your ESP doesn't automatically suppress, implement a process to suppress or remove addresses that repeatedly soft bounce (e.g., after 3-7 consecutive soft bounces on different sends).
• Monitor Bounce Reasons: Understand the specific reasons for soft bounces (e.g., mailbox full, temporary block, general deferral) as some may warrant longer retry periods than others. However, continued bounces for any reason indicate a problem.
• Clean Your List: Regularly clean your email list of consistently unengaged or bouncing addresses to maintain good email list hygiene. This also helps avoid blocklists.
• Sunset Policy: Combine bounce management with a comprehensive sunset policy that removes unengaged subscribers over time, regardless of bounce status, as they can also damage reputation (e.g., via spam complaints).

Key opinions

• Manual Intervention: If an ESP doesn't automatically convert soft bounces to hard bounces or suppress them, marketers often take on the manual task of curating lists and removing or suppressing these addresses.
• Defining Tolerance: There's a strong consensus that a 'soft bounce tolerance' (how many times an address can soft bounce across separate sends before suppression) is crucial, with common suggestions ranging from three to seven bounces.
• ESP Limitations: Some ESPs, despite being industry leaders, may not offer robust automatic soft bounce management, forcing marketers to develop their own internal solutions.
• Beyond Bounces: Marketers also highlight the importance of sunset policies that go beyond just bounce management, removing unengaged subscribers to prevent issues like spam complaints and maintain a healthy list.

Key considerations

• Automate What You Can: If your ESP lacks native automation, explore external tools or integrate with a CRM to automate the suppression of persistently soft bouncing addresses.
• Proactive List Cleaning: Regularly review bounce reports and manually clean your list if automated suppression isn't available, prioritizing addresses that repeatedly soft bounce.
• Advocate for Features: Submit feature requests to your ESP for improved soft bounce handling, as collective requests can drive product development.
• Focus on Engagement: A good engagement strategy (getting opens and clicks) naturally reduces the impact of soft bounces, as engaged users are less likely to have persistent delivery issues.

Key opinions

• Varying Risk Factors: Different soft bounce types carry different risks. For instance, a 'mailbox full' error implies an abandoned mailbox that could become a honeypot, while a 'deferred' message might resolve on its own.
• Long-Term Impact: Even though soft bounces are temporary, their persistence over multiple sends signals to ISPs that the sender is not maintaining a healthy list, leading to reduced trust and poorer inbox placement.
• No one-size-fits-all Solution: There isn't a single correct answer for every soft bounce scenario, as effective management often depends on the specific domain and error code, allowing for varying retry policies.
• Importance of Tolerance: Experts advocate for a 'soft bounce tolerance' policy, where addresses are suppressed after a defined number of separate soft bounces, to proactively manage list quality.

Key considerations

• Define Your Own Policy: If your ESP doesn't offer it, establish internal rules for when to suppress addresses based on repeated soft bounces (e.g., after 3 bounces over 3 weeks), considering lack of engagement.
• Distinguish Bounce Types: Recognize that not all soft bounces are equal; some, like full mailboxes, might indicate abandonment sooner than transient network issues.
• Focus on Data Source: Use bounce data to identify and fix issues at the source of data collection, preventing bad addresses from entering your list in the first place.
• Consider Un-suppression: Some experts even suggest un-suppressing addresses if they show recorded activity (opens/clicks) after a period of soft bouncing, acknowledging the flakiness of email delivery at times.

Key findings

• Temporary vs. Permanent: Documentation consistently defines soft bounces as temporary issues (e.g., full mailbox, server down) and hard bounces as permanent (e.g., invalid address).
• Automatic Conversion: Many ESPs are documented to convert soft bounces to hard bounces after a specified number of attempts or a certain period to prevent long-term deliverability issues.
• Reputation Impact: Official guidelines emphasize that a high bounce rate, including persistent soft bounces, negatively affects sender reputation and inbox placement.
• Suppressing Bounces: It is a standard recommendation to remove hard bounces immediately and to establish policies for suppressing repeatedly soft bouncing addresses.

Key considerations

• Review ESP Policies: Understand your specific ESP's bounce handling policies, including retry schedules and soft bounce conversion thresholds, as these can vary significantly.
• Adhere to Best Practices: Even if your ESP doesn't enforce strict soft bounce suppression, follow industry best practices to protect your sender reputation proactively.
• Utilize Reporting: Leverage bounce reports provided by your ESP to identify trends and specific email addresses that are consistently soft bouncing.
• API Integration: If manual processes are burdensome, explore API integrations with your internal CRM or database to automate bounce data synchronization and suppression, as suggested by some ESP documentation.