How can staggering email sends improve sender reputation and avoid throttling?

Key findings

• Reputation is key: Recipient engagement, not just email categorization, is the primary driver of sender reputation. Even transactional emails can suffer if users do not engage with them positively.
• Avoiding throttling: Spreading out large email volumes helps prevent ISPs from throttling or temporarily blocking your sends, especially for sensitive domains like Microsoft Outlook or Comcast.
• Steady activity: Staggering sends demonstrates a more consistent and steady state of activity for your IP address, which is favored by mailbox providers.
• IP warming: Gradually increasing email volume from new or inactive IPs is essential for establishing a good sender reputation (also known as IP warmup).
• Bounce prevention: Staggering sends can help avoid hard bounces and soft bounces, particularly for large, unengaged lists. This is a critical aspect of optimizing sending speed.

Key considerations

• Engagement first: Even with staggering, if recipients do not engage with your emails, your reputation will still suffer. Focus on sending relevant content to engaged users.
• Identify sensitive ISPs: Be aware that certain ISPs (e.g., Microsoft 365, Comcast) are more sensitive to sending patterns and sudden volume changes. Tailor your staggering strategy accordingly.
• Consistency over bursts: Opt for consistent, smaller sends over time instead of single large monthly blasts to avoid reputation degradation.
• List segmentation: Segmenting your email lists allows for more targeted and staggered sends, especially when dealing with unengaged or old users who still need to receive critical updates.
• Monitor performance: Continuously monitor your sending performance, including bounces, throttling, and IP reputation, to adjust your staggering strategy as needed.

Key opinions

• Staggering benefits: Staggering sends is seen as an effective way to prevent email throttling and reduce bounces, even if it requires additional effort.
• Avoiding overwhelm: Staggering prevents ISPs from becoming overwhelmed by sudden, large volumes, which can lead to emails being rejected or delayed.
• Monthly send challenges: Sending large volumes only once a month can be problematic for reputation, especially with providers like Microsoft, as the IP goes cold and struggles to handle spikes.
• Strategic adjustments: Modifying send schedules (e.g., splitting a monthly send into two) can resolve reputation issues related to inconsistent volume.
• Gradual increase: Gradually warming up sending volume is effective for increasing deliverability, alongside list hygiene.

Key considerations

• Identify problem domains: Marketers should identify which specific domains (e.g., O365, Comcast) are causing deliverability issues to tailor their staggering approach.
• Transactional vs. marketing: Even critical transactional emails need careful handling for unengaged audiences, as lack of engagement still impacts reputation.
• Manage volume spikes: Develop strategies to manage volume spikes, particularly when an IP goes cold between large sends.
• Adapt sending frequency: If monthly sending causes reputation loss, consider increasing send frequency or splitting sends to maintain consistent IP activity.

Key opinions

• Engagement drives reputation: Sender reputation is determined by recipient engagement, not just the type or categorization of email being sent.
• Consistency is vital: Spreading out email sends shows a more steady state of IP activity, which builds a stronger reputation over time, unlike infrequent, large blasts.
• Avoid bursts: Massive sends followed by pauses can be detrimental, as cold IPs struggle with sudden volume.
• Throttling mitigation: Staggering prevents ISPs from throttling email delivery, ensuring messages reach the inbox without delays.
• Long-term health: This practice is crucial for the long-term health of your sender reputation and avoiding issues like being placed on a blocklist (or blacklist).

Key considerations

• User experience focus: Prioritize content that recipients will genuinely interact with, as positive engagement signals override send volume.
• Scheduled versus staggered: While scheduled blasts might be convenient, assess if spreading out the volume is feasible to show consistent IP activity and prevent throttling.
• ISP-specific behavior: Understand how specific ISPs throttle or delay emails to tailor your staggering strategy.
• Impact of cold IPs: Recognize that an IP that goes cold due to infrequent sending will struggle to handle sudden high volumes, impacting deliverability.
• Continuous monitoring: Regularly review your email delivery metrics, including bounces and inbox placement, to identify and address any throttling issues proactively. A positive sender history typically results in higher reputation scores.

Key findings

• Rate limits: ISPs impose sending rate limits to prevent spam and ensure network stability; staggering helps comply with these limits.
• Gradual volume increase: The principle of gradually increasing email volume from a new or inactive email account is fundamental for establishing a good sender reputation (IP warmup).
• Positive sender history: A history of low complaint rates and high engagement from staggered sends leads to higher reputation scores and better deliverability.
• Mitigate throttling: Throttling is a common ISP response to suspicious sending patterns; staggering is a direct countermeasure.
• Segmentation impact: Segmenting email lists is identified as a way to optimize sending speed and improve deliverability by allowing for more manageable batches.

Key considerations

• Consistent delivery: Documentation emphasizes delivering emails consistently, avoiding large, infrequent bursts that can signal suspicious activity.
• Sender reputation protection: Best practices highlight throttling as a method to protect your sender reputation from damage due to unexpected volume.
• Batching strategy: For large email deployments, especially on shared IPs, documentation suggests sending in batches to manage deliverability.
• Database hygiene: Alongside staggering, cleaning databases is crucial to avoid sending to invalid or unengaged addresses, which can lead to bounces and further reputation issues.
• Volume guidelines: Start with small email volumes and gradually increase, as ISPs will monitor and build a profile of your sending activity. This aligns with standard email delivery best practices.