What are recommended email send volume increases to avoid reputation damage and how to recover from hits?

Key findings

• Volume Sensitivity: ISPs like Gmail and Outlook closely monitor sending patterns. Abrupt spikes in email volume, especially when they are far outside a typical sending range, can trigger spam filters and negatively impact domain and IP reputation.
• Recommended Increase: General recommendations for safe email volume increases often fall within a 20-50% increment over average daily, weekly, or monthly send volumes. Exceeding this range significantly can be problematic.
• Volume Proportionality: The impact of a percentage increase can depend on the overall volume. A 50% increase from 100,000 emails to 150,000 might be acceptable, but the same percentage increase from 2 million to 3 million could be perceived as a larger, more suspicious spike by filters.
• Recovery is Possible: Domain reputation can often recover over time with consistent, healthy sending practices. Focusing on sending to engaged subscribers is key to this recovery process.

Key considerations

• Gradual Ramping: To avoid reputation damage, senders should gradually increase their email volume (a process known as ramping up), rather than sending sudden large batches. This consistency helps build trust with ISPs and spam filters.
• Engagement Focus: Prioritize sending to highly engaged segments of your audience, especially when recovering from a reputation hit. This signals positive engagement to ISPs and helps mitigate the impact of previous anomalies.
• Monitor Reputation: Regularly monitor your sender reputation scores using tools like Google Postmaster Tools. This allows for early detection of issues and proactive adjustments to sending strategy.
• Strategic Recovery: If a reputation hit occurs, consider temporarily reducing volume or segmenting to your most engaged users. This can help cool down negative perceptions and allow for a more controlled recovery process. Klaviyo also highlights that ramping involves starting with smaller volumes and then gradually increasing volume over time.

Key opinions

• Volume Fluctuation: Many marketers have experienced reputation hits, particularly with major mailbox providers like Gmail and Outlook, when they've sent bulk communications that drastically increased their typical volume.
• Rule of Thumb: A common guideline shared among marketers suggests that a 20-50% increase in send volume, applied across daily, weekly, and monthly changes, is generally considered safe. Any increase beyond this percentage often leads to problems.
• Engagement as a Remedy: Marketers frequently emphasize that sending to highly engaged subscribers (e.g., those who have engaged in the last 30 days) is crucial for improving and recovering sender reputation after a negative event.
• Consistency is Key: Maintaining a constant volume of emails on a daily basis is seen as a way to sustain sender reputation and decrease the likelihood of emails being flagged by filters.

Key considerations

• Controlled Growth: Marketers should aim to increase volume as gradually as possible to minimize the "shock" effect on filters, which can differ based on baseline volume.
• List Segmentation: When recovering, marketers often recommend segmenting lists to prioritize sending only to the most recently engaged users. This helps to re-establish a positive sending reputation.
• Proactive List Hygiene: Regularly verifying email lists to remove invalid addresses, spam traps, and disengaged subscribers is crucial for improving deliverability and sender reputation, particularly when increasing volume.
• Avoid Spikes: To prevent reputation damage, marketers must consistently manage their email frequency and volume, avoiding sudden increases that can trigger spam filters and result in blocklists. Quora highlights that avoiding sudden spikes in email volume is key to avoiding further reputation harm.

Key opinions

• IP and Domain Reputation: Experts concur that both IP address reputation and domain name reputation are critical factors influencing email deliverability. Any sudden shifts in sending behavior can negatively affect these core reputation metrics.
• Sender Warm-up: For new IPs or domains, a proper email warm-up process is essential, gradually increasing volume to build trust. This principle extends to significant volume increases on existing sending infrastructure.
• Engagement as a Proxy: Mailbox providers use various signals to determine reputation, with user engagement (opens, clicks, replies) being a primary positive indicator. Low engagement rates, especially with high volume, can signal a problem.
• Cooling Down Reputation: One of the fastest ways to improve a bad sender reputation is to temporarily stop sending emails or drastically reduce volume to only the most active segments for a period of 5-7 days.

Key considerations

• Audience Alignment: Experts recommend developing a consistent sending cadence that aligns with your audience's expectations and engagement patterns. This helps avoid triggers for suspicious behavior.
• Reputation Monitoring: Utilizing email reputation checker tools and postmaster tools (e.g., Google Postmaster Tools) is vital for understanding reputation scores and identifying issues early. Twilio suggests using these tools to improve deliverability.
• DMARC Implementation: Implementing and monitoring DMARC (along with SPF and DKIM) is crucial for email authentication and reputation protection, particularly when dealing with varying sending volumes.
• Targeted Recovery: When reputation is low, experts advise a ramp-up strategy that involves slowly reintroducing volume to segments with the highest engagement to rebuild trust with ISPs effectively.

Key findings

• Sender Reputation Components: Documentation outlines that sender reputation is a complex score based on various factors, including IP address reputation, domain reputation, spam complaint rates, and bounce rates. Volume consistency directly impacts these metrics.
• Anti-Spam Measures: Mailbox providers use sophisticated algorithms to detect unusual sending patterns, which can include sudden volume spikes, as potential indicators of spam or abuse. These algorithms are designed to protect their users from unwanted mail.
• Engagement Metrics: Key engagement metrics (opens, clicks, unsubscribes, spam reports) are heavily weighted by ISPs. Documentation suggests that low engagement or high complaints, especially with increased volume, will negatively impact deliverability.
• Warm-up as Standard: Official guides often include recommendations for gradual warm-up of new IPs or domains, emphasizing the need to build a positive sending history over time rather than attempting large initial sends.

Key considerations

• Consistency over Quantity: Documentation consistently advises maintaining a stable and predictable sending volume. Deviations from this norm, even for legitimate campaigns, can be misinterpreted as malicious behavior by automated systems.
• List Quality: High bounce rates, spam complaints, and engagement with spam traps are red flags. Documentation stresses the importance of list hygiene and permission-based sending to ensure emails reach engaged recipients.
• Utilize Feedback Loops: Many ISPs offer feedback loops (FBLs) that provide data on spam complaints. Documentation encourages senders to use these to identify and remove complainers from their lists, which is crucial for reputation recovery.
• Postmaster Tools: Platforms like Google Postmaster Tools are officially recommended for monitoring sender reputation, spam rates, and delivery errors. Regular review of these tools can help diagnose and address volume-related deliverability issues.
• Authentication Standards: Adhering to email authentication protocols such as SPF, DKIM, and DMARC is consistently highlighted as a foundational requirement for establishing and maintaining sender trust, regardless of sending volume. Proper authentication helps ISPs verify the legitimacy of your emails.