What causes high bounce rates on Cyber Monday and how to prevent them?

Key findings

• Volume surge: A significant increase in email volume during peak holiday periods like Cyber Monday can strain your sending reputation, especially with specific internet service providers (ISPs).
• ISP sensitivity: Smaller or regional domains, often consolidating under larger entities (e.g., SBCGlobal, Bellsouth, and AT&T are all under AT&T's umbrella), may have stricter or less forgiving spam filters that are easily triggered by uncharacteristic sending patterns or increased volume.
• Soft bounces predominate: While soft bounces are temporary, a high volume of them indicates that emails are reaching the recipient server but are being deferred or rejected due to reputation, content, or temporary server issues.
• List quality impact: Even a 'good' list can have segments with lower engagement or older data that become problematic under high-pressure sending conditions, pushing deliverability into a 'spam' folder or triggering bounces.

Key considerations

• Monitor specific domains: Pay close attention to bounce rates from specific domains, especially those known for strict filtering or those representing a significant portion of your audience. For example, emails to AT&T, SBC, and Bellsouth domains often require specific attention.
• Analyse bounce codes: If your email service provider allows, dig into the specific bounce codes and responses. This granular data provides precise reasons for rejections and can help pinpoint issues, whether it's related to soft bounce rates or poor inbox placement.
• Review sending practices: Ensure your email sending practices align with ISP guidelines, particularly during high-volume events. This includes proper authentication and maintaining a clean sender reputation.
• Strategic segmentation: Segment your email list and prioritize sending to your most engaged subscribers first, especially during critical sales periods, to maintain positive engagement metrics with ISPs.

Key opinions

• Unusual activity: Marketers often find that uncharacteristic sending volume during holidays flags their campaigns as suspicious, even if the list is generally reliable.
• Hidden list issues: While a list might seem good based on opens and clicks, it can still contain problematic data points (e.g., old or inactive subscribers) that only cause issues when sending at scale.
• Lack of visibility: Many marketing platforms do not provide granular bounce codes, making it difficult to diagnose the precise cause of high bounce rates. This lack of insight necessitates additional investigative steps.
• ISP consolidation: The observation that multiple smaller domains (like Bellsouth, SBCGlobal) share the same underlying mail infrastructure (e.g., AT&T) indicates that a problem with one might affect all, highlighting the need to understand ISP relationships.

Key considerations

• Pre-holiday testing: Before peak events like Black Friday and Cyber Monday, conduct smaller sends to test your deliverability with key ISPs, especially if planning significantly higher volumes.
• List segmentation: Prioritize your sends by segmenting your list into highly engaged, moderately engaged, and less engaged groups. Send to your best segments first to establish positive sending patterns.
• Inactivity review: Regularly identify and analyze the least active portions of your list (e.g., the oldest 5% of data) to understand their impact on overall deliverability. This can help improve email deliverability for future campaigns.
• Manage expectations: Educate internal stakeholders (e.g., 'bosses') on the risks of 'maximizing' list usage, especially during high-stakes periods, emphasizing that quantity does not always equate to quality in email marketing.

Key opinions

• Contextual filtering: During busy periods like Black Friday, receiving servers are under stress and may implement more aggressive or arbitrary filtering decisions due to resource constraints, even for otherwise compliant senders.
• Borderline status: Senders who are typically 'okay' but not top-tier in terms of reputation can become 'borderline' during volume spikes, leading to increased bounces that resolve once volume returns to normal.
• List quality's subtle role: While a list might appear active, it often contains hidden pockets of data (e.g., the least active, oldest segments) that contribute negatively to reputation and become more apparent during high-volume sends.
• ISP-specific issues: Certain ISPs (like AT&T, which includes sbcglobal.net and bellsouth.net) may have specific policies or higher sensitivity to volume surges, making them prone to higher bounce rates for senders experiencing uncharacteristic sending behavior.

Key considerations

• Analyze historical data: Regularly analyze your email list for segments with low activity or age. Understanding the behavior of these 'bad pots of data' can prevent future deliverability issues, especially during high-volume events. This is key to recovering domain reputation.
• Segment sending strategy: To mitigate risks, split your email list into 2-3 segments based on engagement. Send to the most engaged segment first, then the next best, and so on. This approach helps maintain positive sending metrics. This can also help when figuring out how to reduce soft bounces after volume spikes.
• Direct ISP communication: For persistent issues with specific ISPs, consult their postmaster pages directly. For example, the AT&T Postmaster site provides guidelines for senders.
• Proactive list cleaning: Instead of just suppressing unengaged users, consider removing the truly inactive segments before high-volume sends to prevent them from negatively impacting your sender reputation.

Key findings

• System failures: Documentation emphasizes that backend system failures or capacity issues, while more commonly associated with website performance, can also indirectly impact email deliverability by causing recipient mail servers to defer or reject incoming messages under heavy load.
• Page load speed: Many sources indicate that slow loading times for web pages linked in emails can lead to high bounce rates from the website perspective, discouraging engagement even if the email delivered successfully.
• Mobile usability: Given that a significant portion of holiday shopping occurs on mobile devices, poor mobile responsiveness of landing pages linked in emails can increase bounce rates.
• User experience: Content that is irrelevant, overwhelming (e.g., too many pop-ups), or difficult to navigate contributes to users 'bouncing' from a page, reflecting a broader principle of user dissatisfaction that can apply to the entire email journey.

Key considerations

• Technical infrastructure: Ensure your email sending infrastructure (and linked website infrastructure) is robust enough to handle the increased volume of Cyber Monday. This includes optimizing server response times and database performance.
• Content optimization: Optimize email content and linked landing pages for clarity and relevance. Minimize distracting elements and ensure clear calls to action to guide the user journey. This relates to how email click-through rate is improved.
• Mobile-first approach: Design emails and landing pages with mobile users in mind. A seamless mobile experience is crucial for reducing bounce rates during peak shopping events. This is also covered in our guide on boosting email deliverability rates.
• Load testing: Perform load testing on your website and email systems before Cyber Monday to identify and address potential bottlenecks that could lead to high bounce rates or system failures.