What are good email engagement thresholds for deliverability monitoring?

Key findings

• Complaint rates: Many experts consider anything above 0.1% to be a risk, with modern standards pushing for even lower thresholds. Major mailbox providers like Gmail and Yahoo now require complaint rates below 0.3% to maintain good standing.
• Bounce rates: Hard bounce rates, indicating permanent delivery failures, should ideally be below 3%, with some suggesting a maximum of 4-8%. High hard bounces, especially in welcome streams, often point to a data acquisition problem or poor email list quality. Soft bounces, though temporary, still need careful monitoring.
• Deliverability rate: A good average deliverability rate, representing emails successfully reaching the inbox, typically hovers between 90% to 98%. Rates consistently below 95% often indicate significant deliverability issues.
• Engagement ratios: Beyond raw rates, ratios such as open-to-unsubscribe and open-to-spam provide deeper insights, revealing if high unsubscribe or complaint rates are masked by a large segment of unengaged subscribers. Monitoring these per-mailbox provider is particularly effective.
• Open rates: While industry benchmarks for open rates typically fall between 20% and 30%, a good open rate can vary widely based on industry, audience, and content. A noticeable dip below 20% warrants investigation.

Key considerations

• Industry and audience: Thresholds for B2B sending may differ significantly from B2C due to varying complaint frequencies and engagement patterns.
• Holistic view: Deliverability is influenced by numerous factors beyond just these rates, including sender reputation, email authentication (SPF, DKIM, DMARC), list quality, and content relevance. It's vital to consider all elements together to understand your email performance properly. For a comprehensive overview, see Mailgun's State of Email Deliverability.
• Historical performance: While industry averages are helpful, benchmarking against your own historical performance for specific segments provides a more accurate picture of improvement or decline.
• Proactive list management: Regularly cleaning your list by removing unengaged subscribers (e.g., those inactive for 90-180 days) is a critical practice to maintain good engagement metrics and avoid being flagged by ISPs. Learn how to manage unengaged subscribers.

Key opinions

• Visualizing engagement: Many marketers use conditional formatting to visualize engagement levels, helping them quickly identify areas needing attention, such as high bounce or abuse rates.
• Abuse rate adjustments: There's a consensus that abuse (spam complaint) rates should be very low, with a common suggestion to keep them under 0.1%, or even as low as 0.05% for 'green' status.
• Hard bounce issues: Unexpectedly high hard bounce rates, particularly in initial engagement campaigns like welcome streams, often signal underlying data acquisition problems that require immediate attention.
• Beyond simple rates: Some marketers find value in analyzing ratios like open-to-unsubscribe and open-to-spam. These metrics can uncover issues like high complaint rates being obscured by a large proportion of unengaged subscribers who aren't even opening emails.

Key considerations

• Business model impact: The type of business (B2C vs. B2B) influences appropriate complaint thresholds, with B2B often allowing for slightly more aggressive rates due to different complaint frequencies.
• Contextual relevance: Marketers recognize that absolute thresholds are always relative and depend on factors such as subject line, preview text, and the overall email creative and content. This highlights the ongoing need to optimize email content for engagement.
• List hygiene: Ensuring a clean email list by removing inactive subscribers (e.g., those with no engagement in the last 180 days) is a common recommendation to maintain healthy engagement rates. This also contributes to positive sender reputation.
• Unsubscribe rates: A general goal is to keep unsubscribe rates below 0.3% per email campaign, regardless of the specific industry. For further insights on this, refer to Klaviyo's guide on deliverability monitoring.

Key opinions

• Dynamic thresholds: Experts agree that what was an acceptable complaint rate in the past (e.g., > 0.1%) is now much lower. ISP filtering algorithms are constantly evolving, making thresholds dynamic and requiring continuous adaptation.
• Beyond raw numbers: It is crucial to analyze engagement metrics at a granular level, ideally per-mailbox provider, to gain more actionable insights. This helps in understanding specific deliverability challenges with different ISPs.
• Engagement as a core factor: Successful email delivery and inbox placement are increasingly dependent on positive recipient engagement. Low engagement almost inevitably leads to filtering into spam or even blocklisting.
• Proactive monitoring: Effective deliverability extends beyond simply avoiding blacklists. It requires a proactive approach to monitoring all engagement metrics to ensure active inbox placement and maintain a strong sender reputation.

Key considerations

• List segmentation: Segmenting audiences based on their engagement levels allows for tailored content and sending frequencies, which can significantly improve overall sender health and reduce negative feedback. This directly influences how to rebuild sender reputation.
• Consistency and feedback: Consistent sending practices and positive recipient interactions are fundamental to building IP and domain reputation. Ignoring recipient feedback, such as spam complaints or low open rates, is detrimental, as ISPs are highly responsive to user behavior. Read more on SpamResource for further insights.
• Historical benchmarking: In addition to general industry benchmarks, experts recommend averaging a segment's previous year's engagement numbers. This allows for a comparison against historical performance, providing a more accurate assessment of current trends.
• Data acquisition quality: High hard bounce rates, even in welcome streams, indicate issues with data acquisition. Addressing the source of invalid email addresses is critical for maintaining list health. See Email Deliverability Issues for more.

Key findings

• Spam complaint rate: Major senders are required to maintain a spam complaint rate below 0.3%, with best practices suggesting keeping it even lower, ideally below 0.1% to avoid reputation damage.
• Delivery rate: A healthy email delivery rate (messages successfully delivered) is generally considered to be 95% or higher, indicating a good quality email list and effective inbox placement strategies.
• Bounce rate: Hard bounce rates exceeding 3% are a red flag and indicate potential issues with email list validity or acquisition practices.
• Subscriber engagement: Sending only to engaged subscribers (e.g., those active within the last 90-120 days) is a key best practice for maintaining strong deliverability and a positive sender reputation.

Key considerations

• Authentication: Proper email authentication with SPF, DKIM, and DMARC is fundamental for deliverability, often mandated by major ISPs alongside engagement thresholds. A strong DMARC policy, like p=none to start, is a critical component.
• Open rates as a metric: While a good open rate can be above 20%, documentation often advises caution if it dips lower, acknowledging that a slight drop might not immediately signal a problem but warrants monitoring. This is particularly relevant for re-engagement strategies.
• Content quality: Beyond technical metrics, the quality and relevance of email content are vital for driving engagement and positive recipient interactions, directly influencing inbox placement.
• Monitoring: Continuous monitoring of email list health, including bounce and complaint rates, is a foundational best practice recommended by almost all authoritative sources to identify and mitigate deliverability risks. Refer to EmailTooltester for deliverability best practices.