Summary
Email bounce rates are a critical metric for understanding your email deliverability, yet their calculation and what constitutes a good bounce rate often lead to confusion. This summary aims to clarify how bounce rates are typically calculated across the industry and provide context for interpreting these figures to ensure your email campaigns are as effective as possible.
Key findings
- Calculation basis: Email bounce rate is generally calculated by dividing the total number of bounced emails by the total number of emails sent, then multiplying by 100 to get a percentage. For example, if you send 1,000 emails and 20 bounce, your bounce rate is 2%.
- Bounce types matter: There are two primary types of bounces: hard bounces and soft bounces. Hard bounces are permanent delivery failures (e.g., invalid email address), while soft bounces are temporary (e.g., full inbox, server issues). Understanding this distinction is crucial for accurate interpretation.
- Industry benchmarks: A good email bounce rate is generally considered to be 2% or less, particularly when referring to hard bounces. While some benchmarks might include both hard and soft bounces, a lower percentage is always indicative of a healthier list.
- Beyond delivery: An email that delivers but lands in the spam folder is not counted as a bounce. Bounces specifically refer to emails that could not be delivered to the receiving server at all within the allotted retry period or were rejected outright.
Key considerations
- Clarity in benchmarks: When comparing your bounce rates to industry benchmarks, always seek to understand whether the benchmark includes hard bounces, soft bounces, or both. This transparency is vital for a meaningful comparison, as highlighted by Constant Contact's approach.
- Sender reputation impact: High hard bounce rates signal to Internet Service Providers (ISPs) that your list quality is poor, which can negatively impact your sender reputation and deliverability for future campaigns.
- List hygiene: Regularly cleaning your email list to remove invalid or inactive addresses is paramount. This proactive approach helps to maintain a low bounce rate and improve overall inbox placement.
- ESP variance: Different Email Service Providers (ESPs) may have slightly varied methods for classifying and reporting bounces. It is important to understand how your specific ESP defines and accounts for various bounce types in its reporting.
What email marketers say
Email marketers often find industry bounce rate benchmarks to be a source of confusion and frustration, noting that reported figures often seem artificially low compared to their real-world experiences. This discrepancy typically stems from differing definitions of what constitutes a bounce, particularly concerning hard versus soft bounces.
Key opinions
- Benchmark ambiguity: Many industry benchmarks fail to explicitly distinguish between hard and soft bounces, leading to an unclear understanding of the reported percentages.
- Misleading low rates: Marketers frequently perceive published bounce rates of 1.5-2% as artificially low because their own experiences suggest higher figures, especially when considering emails that go to spam as a form of non-delivery (though technically not a bounce).
- Contextual understanding: Marketers recognize that interpreting bounce rates requires knowing the specific calculation method used by the reporting entity, as some count all bounces while others focus solely on hard bounces.
- Industry variability: Bounce rates can vary significantly across different industries due to varying list hygiene practices, audience demographics, and sending volumes.
Key considerations
- ESPs' calculation methods: Marketers should always verify how their ESP calculates delivered rates, whether it’s total sent - all bounces or total sent - hard bounces only. This affects the perceived bounce rate.
- Defining a bounce: It is critical for marketers to clearly understand that a bounce means non-delivery, not necessarily being filtered as spam. If the email is accepted by the receiving server, it's considered delivered.
- Impact of list quality: High bounce rates, particularly hard bounces, often indicate poor list hygiene and can severely affect campaign performance and sender reputation. Regular validation is key.
- Focus on deliverability: Instead of chasing low bounce rate benchmarks, marketers should prioritize strategies that ensure actual inbox placement and engagement, such as proper list management and segmentation, as a lower bounce rate supports better deliverability.
Email marketer from Email Geeks explains that many industry benchmarks on bounce rates do not clearly differentiate between hard and soft bounces. This lack of distinction can make it difficult for marketers to understand whether the reported percentages align with their specific campaign outcomes and list health.
Email marketer from Outfunnel suggests that a healthy email bounce rate benchmark is generally considered to be 2% or less. This figure typically indicates good list quality and effective email deliverability strategies, helping to maintain positive sender reputation over time.
What the experts say
Experts in email deliverability emphasize that industry benchmarks for bounce rates can often be misleading due to inconsistencies in how different ESPs define and report bounces. They stress the importance of understanding the precise definitions of hard and soft bounces, as well as the underlying methodologies, to accurately assess email campaign performance and maintain a healthy sending reputation.
Key opinions
- Defining bounce types: A clear, consistent definition of hard and soft bounces is fundamental before any meaningful discussion or comparison of bounce rates can occur.
- Beyond the numbers: Merely looking at a low bounce rate benchmark is insufficient; understanding the factors contributing to bounces, such as list quality and recipient engagement, is more valuable.
- Spam vs. bounce: An email reaching the recipient's server but being filtered into spam is a delivery success, not a bounce. Bounces indicate a failure to reach the mail transfer agent (MTA) or a permanent rejection.
- Data transparency: Any entity publishing email bounce rate statistics should clearly outline their calculation methodology, including how they account for both hard and soft bounces.
Key considerations
- Accurate definition: Email deliverability experts stress that a bounce occurs when an email cannot be delivered within the allotted retry period or is rejected outright by the receiving MTA. This strict definition helps maintain accurate metrics.
- Queue management: For a well-managed email program, temporary failures or emails sitting in the queue should be rare. Efficient retry policies and suppression lists are crucial to minimize such occurrences.
- Continuous list hygiene: Actively managing and cleaning your email lists, particularly by removing hard bounces promptly, is essential for preserving sender reputation and ensuring that your messages reach valid inboxes. Neglecting this can lead to being added to an email blocklist or blacklist.
- Monitoring spam signals: ISPs frequently interpret attempts to send emails to non-existent addresses as a significant spam signal, which can lead to poorer inbox placement even for valid recipients. Monitoring these spam signals is as important as tracking bounce rates.
Email expert from SpamResource suggests that the definition of a bounce is critical for accurate reporting and analysis. Without a consistent and clear understanding of what constitutes a hard versus a soft bounce, comparisons between different email campaigns or industry benchmarks can be misleading and unhelpful for optimizing deliverability.
Email expert from WordToTheWise explains that simply achieving a low bounce rate is not enough; the true measure of success lies in whether emails actually reach the inbox and engage recipients. Focusing solely on bounce rates can overlook issues like spam folder placement or poor engagement, which also hinder email marketing effectiveness.
What the documentation says
Official documentation and technical standards define email bounces primarily based on SMTP (Simple Mail Transfer Protocol) responses. These define whether an email could not be delivered temporarily (soft bounce) or permanently (hard bounce). The core principle remains consistent: a bounce occurs when the receiving mail server explicitly rejects or is unable to accept an email.
Key findings
- SMTP response codes: Bounces are directly tied to specific SMTP error codes received from the recipient's mail server. Codes in the 5xx range (e.g., 550 User unknown) typically indicate hard bounces, while 4xx codes (e.g., 450 Mailbox unavailable) suggest soft bounces.
- Delivery confirmation: An email is considered delivered once the sending server receives a 2xx success code from the recipient's mail server, indicating acceptance. This means the email has successfully passed through the initial delivery stage, regardless of subsequent spam filtering.
- No delivery, no bounce: Documentation supports the view that a bounce specifically means a failure to deliver the email to the receiving MTA, rather than an email being placed into a spam folder after successful delivery.
- Retry periods: For soft bounces, sending systems typically retry delivery over a defined period before ultimately classifying the email as a hard bounce or a permanent failure.
Key considerations
- Adhering to standards: Following established SMTP protocols and understanding the significance of each bounce code is essential for accurate bounce processing and maintaining good deliverability practices.
- Classification accuracy: Accurate classification of bounces into hard or soft categories based on official definitions (e.g., as outlined in RFCs) allows for appropriate suppression strategies.
- Impact on sender reputation: Documentation often implies that repeated attempts to send to permanently invalid addresses (hard bounces) negatively impact sender reputation, leading to increased scrutiny from ISPs and potential blocklisting.
- Monitoring delivery: While bounce rates are important, a complete understanding of email performance requires monitoring delivered rates and inbox placement, as well as bounce metrics, as suggested by AWS documentation.
Documentation from Segment explains that to calculate your email bounce rate, you should divide the number of bounces received by the total number of emails sent in a campaign, and then multiply this result by 100. This formula provides a straightforward way to quantify the proportion of undeliverable messages, serving as a fundamental metric for email campaign analysis.
Documentation from AWS states that bounce rate calculation often uses representative volume, meaning it can span back in time depending on your sending rate. This approach allows for a more stable and accurate measure of bounce performance, especially for senders with fluctuating email volumes, providing a consistent view over a broader period.
