How is email bounce rate calculated?

To calculate your email bounce rate, divide the number of bounced emails by the total number of emails sent, then multiply by 100 to get a percentage. This provides the overall bounce rate for your campaign or sending period. For a deeper understanding, you should also break this down into hard and soft bounces.

What is considered a good email bounce rate?

A good email bounce rate is generally considered to be below 2%. Some industries may tolerate up to 5%, but aiming for less than 2% is ideal for maintaining excellent sender reputation and strong deliverability. Consistently higher rates, especially above 5-10%, can indicate serious list hygiene issues or other problems.

What's the difference between hard and soft bounces?

Hard bounces are permanent delivery failures, like non-existent email addresses, and should be removed from your list immediately. Soft bounces are temporary issues, such as a full inbox, and indicate that the email might be delivered later. While less critical, repeated soft bounces to the same address can still harm your reputation and should be addressed.

Why is it important to measure bounce rate by campaign or mailbox provider?

Measuring your bounce rate by specific campaigns or by individual Mailbox Providers (MBPs like Gmail or Outlook) allows you to pinpoint issues more accurately. For instance, a high bounce rate only for a particular MBP might indicate a specific filtering issue or reputation problem with that provider, requiring a tailored solution.

What are the key strategies to reduce your email bounce rate?

To reduce bounce rates, focus on email list hygiene: use email validation at signup, regularly clean your list to remove hard bounces and inactive addresses, and segment your audience for more targeted sending. Analyzing SMTP bounce replies also helps diagnose specific problems for undelivered emails.

How should bounce rate be measured to maintain a healthy email reputation? - Sender reputation - Email deliverability - Knowledge base

Maintaining a healthy email reputation is crucial for any successful email marketing strategy. One of the most significant indicators of your sending health is your bounce rate. If emails aren't reaching their intended recipients, it signals to mailbox providers that your sending practices might be problematic, leading to poorer inbox placement and even blacklisting (or blocklisting).

However, simply looking at a global bounce rate number isn't enough. To truly understand and maintain a positive sender reputation, you need to measure and analyze your bounce rate with a finer-toothed comb. This involves understanding the nuances of different bounce types and monitoring them across various segments of your email campaigns.

We'll explore how to effectively measure bounce rate, distinguish between different types of bounces, and utilize this data to protect and enhance your email deliverability.

Understanding email bounce rate

Before diving into measurement, it's essential to grasp what an email bounce truly is. A bounce occurs when an email cannot be delivered to the recipient's server. This non-delivery isn't always a bad sign, but a consistently high bounce rate can severely damage your sender reputation and lead to your emails being flagged as spam or blocked entirely by Internet Service Providers (ISPs).

Bounces fall into two main categories: hard bounces and soft bounces. Each type requires a different approach to management. A hard bounce indicates a permanent delivery failure, meaning the email address is invalid, non-existent, or blocked. These should be removed from your list immediately. On the other hand, soft bounces are temporary issues, such as a full inbox or a server being temporarily down. While less critical than hard bounces, repeated soft bounces to the same address can still negatively impact your deliverability.

Understanding this distinction is the first step in effective bounce rate measurement. Many Email Service Providers (ESPs) automatically handle these, but it is important for you to be aware of the underlying mechanisms. A deep dive into acceptable email bounce rates for both hard and soft bounces is fundamental for maintaining a healthy sending environment.

Key metrics and calculation

To calculate your email bounce rate, the standard formula is straightforward: divide the number of bounced emails by the total number of emails sent, then multiply by 100 to get a percentage. For example, if you send 10,000 emails and 200 bounce, your bounce rate is 2%.

While your ESP will likely provide this metric, knowing the calculation helps in understanding the underlying data. As for what constitutes a good bounce rate, industry benchmarks generally suggest aiming for less than 2%. Some sources, like Amazon Simple Email Service, recommend keeping it below 5% for optimal deliverability. Anything consistently above 5-10% indicates serious issues that need immediate attention.

It's not just the overall percentage that matters; the underlying data provides richer insights. This is where segmenting your bounce data becomes critical. Below is a simple table to illustrate common bounce rate thresholds:

Bounce rate percentage	Impact on reputation
Under 2%	Excellent, healthy email sending reputation.
2-5%	Generally acceptable, but monitor closely for increases. Most industries perform well here.
5-10%	Warning zone. Indicates potential list quality issues or content problems. Risk of being blocklisted.
Above 10%	Critical. Severe damage to sender reputation. Emails will likely go to spam or be rejected. Requires immediate action.

Beyond the general percentage, focusing on your hard bounce rate specifically is paramount, as this is the most damaging type of bounce to your email sender reputation.

Granular measurement for impact

To genuinely maintain a healthy email reputation, you need to go beyond aggregate numbers. Measuring your bounce rate per campaign is a good start. This allows you to identify specific campaigns or list segments that might be underperforming or contain problematic addresses. For instance, a campaign sent to an older list segment might have a higher bounce rate compared to a newly acquired list.

Furthermore, analyzing bounce rates by mailbox provider (MBP) is extremely valuable. A high bounce rate specific to

Google,

Outlook, or

Yahoo can highlight a specific issue with that provider, rather than a global problem. This granular view allows for targeted troubleshooting and adjustments to your sending strategy. For instance, you might need to adjust sending volume or content specifically for certain MBPs.

Typical bounce reporting

Aggregate data: Most ESPs provide an overall bounce rate, which is useful for a quick health check.
Campaign-level: Bounce rates broken down by individual email campaigns.
Basic categorization: Separation into hard and soft bounces.

It is also crucial to monitor bounce rate by day or week to spot trends. A sudden spike can indicate an issue with a new list segment, a content filter triggering a blocklist (or blacklist), or a problem with your sending infrastructure. Additionally, paying attention to SMTP replies provides valuable context for bounce reasons, helping you understand whether it's a permanent rejection, a temporary deferral, or a content-related block.

Strategies for maintaining a healthy rate

Minimizing your bounce rate is key to maintaining a healthy sender reputation. The most effective strategy begins with robust list hygiene. Regularly cleaning your email lists ensures that you are not sending to invalid or inactive email addresses, which are primary contributors to hard bounces. This includes validating new sign-ups and segmenting your audience effectively to send relevant content.

Beyond list cleaning, actively monitoring your bounce data and taking prompt action is vital. If you observe a persistent soft bounce from a specific address, it may be time to remove it from your active list. This proactive management helps prevent temporary issues from turning into long-term deliverability problems that could affect your domain reputation.

Best practices for reducing bounce rates

Email validation: Use a real-time email validation service during sign-up to prevent invalid addresses from entering your list.
Regular list cleaning: Periodically remove hard bounces and inactive subscribers from your email lists.
Segmentation: Segment your audience and tailor content to improve engagement and reduce bounces.
Monitoring: Keep a close eye on bounce rates by campaign and by Mailbox Provider (MBP) to spot specific issues.
SMTP analysis: Understand SMTP replies to differentiate between temporary and permanent bounce reasons.

By implementing these strategies, you can significantly reduce your bounce rate, which in turn leads to better inbox placement and a stronger email sending reputation. This proactive approach is critical for long-term email marketing success.

Views from the trenches

Best practices

Monitor bounce rates per campaign and by Mailbox Provider (MBP), not just globally, for targeted insights.

Remove hard bounces immediately and manage persistent soft bounces by ceasing further sending to those addresses.

Analyze SMTP bounce codes to understand specific reasons for non-delivery and take appropriate action.

Implement email validation at point of collection to prevent bad addresses from entering your list.

Regularly clean your email list to remove old or inactive addresses that may turn into hard bounces.

Common pitfalls

Overlooking daily or weekly bounce rate spikes, which could indicate a new issue with list quality or filtering.

Failing to differentiate between hard and soft bounces, leading to unnecessary removal or retention of addresses.

Ignoring SMTP reply codes, missing crucial diagnostic information about why emails are not being delivered.

Not segmenting bounce data by Mailbox Provider (MBP), missing provider-specific deliverability issues.

Maintaining large lists with unengaged subscribers, increasing the likelihood of bounces and reputation damage.

Expert tips

For transactional emails, even a slightly elevated bounce rate can be critical, as these often have higher expectations for delivery.

Consider a tiered approach to list cleaning; remove hard bounces instantly, but give soft bounces a few retries before suppression.

Some bounces, like 'mailbox full', are temporary, but repeated occurrences should prompt list removal for that subscriber.

A sudden increase in 'too old' bounce responses indicates an issue with campaign timing or list segmentation.

Always align your bounce rate analysis with your specific sending goals—monitoring for reputation requires different metrics than proving campaign effectiveness.

Expert view

Expert from Email Geeks says that analyzing bounce rate per campaign, especially after 24 hours to account for MTA queues, provides a better picture than global metrics.

2024-02-15 - Email Geeks

Marketer view

Marketer from Email Geeks says that monitoring bounce rates by individual Mailbox Providers (MBPs) is critical for identifying specific deliverability problems.

2024-03-01 - Email Geeks

Key takeaways for a healthy email reputation

Measuring bounce rate effectively is more than just looking at a single number. It requires a nuanced understanding of hard versus soft bounces, granular analysis by campaign and mailbox provider, and continuous monitoring of trends over time. By adopting these comprehensive measurement practices, you can gain actionable insights into your email deliverability and maintain a robust sender reputation.

Remember, a low bounce rate is a strong signal of a healthy and engaged email list, which is foundational for successful email marketing. Proactive management and detailed analysis will ensure your messages consistently reach the inbox.