How do email acceptance, hard bounce, and block bounce rates differ for SaaS companies?

Email acceptance is the initial successful hand-off of an email to the recipient's server. A hard bounce is a permanent delivery failure due to an invalid address. A block bounce (or blacklist bounce) occurs when an email is rejected because your sending IP or domain is on a blocklist. Each indicates a different stage of delivery failure and requires specific attention.

What's the biggest factor influencing these rates for SaaS email deliverability?

List hygiene is arguably the biggest factor. Sending to old, unverified, or incorrect email addresses leads to high hard bounces and can trigger spam traps, which then contribute to block bounces and a lower acceptance rate. Regularly cleaning your list and using double opt-in are crucial practices.

How often should SaaS companies monitor these key deliverability metrics?

SaaS companies, particularly those sending high volumes or on behalf of clients, should monitor these metrics daily or at least weekly. Real-time monitoring allows for quick identification and resolution of issues before they escalate and severely impact sender reputation and overall deliverability.

Can transactional emails have different bounce rates than marketing emails for SaaS?

Transactional emails, like password resets or order confirmations, generally have lower bounce rates and higher acceptance rates than marketing emails because they are expected by the recipient and often triggered by user action. However, poor list management for transactional emails can still lead to deliverability issues.

What are best-in-class email acceptance, hard bounce, and block bounce rates for SaaS companies? - Sender reputation - Email deliverability - Knowledge base

For SaaS companies, understanding email deliverability metrics like acceptance, hard bounce, and block bounce rates is crucial for maintaining a strong sender reputation and ensuring messages reach the inbox. While industry benchmarks can provide a general idea, true success comes from a nuanced approach, acknowledging that the definition of a "good" rate can vary based on your specific sending practices and list hygiene.

My focus is always on ensuring that every email sent on behalf of our customers has the best possible chance of being delivered. This involves continuously monitoring these key metrics and implementing best practices to keep our email streams healthy. It's not just about hitting a number, but about building a robust sending infrastructure and nurturing a positive sending relationship with mailbox providers.

What constitutes best-in-class for these rates often surprises people, as there's a difference between what's generally acceptable and what truly sets a sender apart. Let's delve into what these rates mean and what SaaS providers should realistically aim for.

Understanding email acceptance rates

Email acceptance rate, sometimes referred to as delivery rate, measures the percentage of emails that an email service provider (ESP) or recipient server initially accepts. It's the first hurdle your email has to clear. A high acceptance rate indicates that your sending IP and domain are not immediately flagged as suspicious, allowing your messages to proceed to further filtering.

For SaaS companies, especially those sending transactional or critical workflow emails on behalf of thousands of customers, aiming for a very high email acceptance rate is paramount. Anything below 98-99% warrants immediate attention, as it suggests a fundamental issue with your sending reputation or the quality of the recipient addresses. While a 90% acceptance rate might seem high to some, it's often a clear indicator that your list or list collection practices need significant improvement.

It is important to remember that acceptance does not guarantee inbox placement, as accepted emails can still be routed to the spam folder. However, it is the essential first step. Maintaining a consistent acceptance rate is a key indicator of the overall health of your email program. You can learn more about acceptable rates and the different types of bounces in our article on acceptable email bounce rates.

Metric	Best-in-Class	Acceptable	Problematic
Email Acceptance Rate	>99%	98-99%	<98%

Decoding hard bounce rates

A hard bounce signifies a permanent delivery failure, meaning the email address is invalid, nonexistent, or blocked indefinitely. These are serious and directly impact your sender reputation, as they signal to mailbox providers that you might be sending to old or unverified lists. Continuing to send to hard bounced addresses is detrimental to your deliverability.

For SaaS companies, the goal for hard bounce rates should be as low as possible. MailerLite and Biscred suggest aiming for a general email bounce rate of less than 2%, while others recommend keeping it under 2-3% overall. Specifically for hard bounces, if it’s the first email to an address, a rate between 2-3% might be seen, but on an ongoing basis, this should drop significantly, ideally below 1%. Some even argue that anything above 0.40% is high, according to Quora discussions on hard bounces. Immediately removing these addresses from your lists is critical for maintaining a good sender reputation.

High hard bounce rates can quickly lead to your IP or domain being added to blacklists, which will significantly impair your ability to reach the inbox for all your customers. Proactive list cleaning and double opt-in processes are essential to prevent hard bounces. You can review how email service providers manage these rates in our article on soft and hard bounces.

Initial contact

When sending to a new list or newly acquired contacts, a hard bounce rate of 2-3% might occur. This is often due to natural list decay, typos, or old email addresses in the acquisition source. The goal is to identify and remove these quickly.

Ongoing campaigns

For established lists and regular campaigns, the hard bounce rate should be consistently below 1%, ideally approaching 0%. A low ongoing hard bounce rate signifies excellent list hygiene and validates the quality of your recipient data.

Minimizing block bounce rates

Block bounces, sometimes referred to as 'blocklist bounces' or 'rejection due to policy,' occur when a recipient's mail server outright rejects your email due to your sending IP or domain being listed on a blocklist (or blacklist) or violating strict server policies. This is a severe deliverability issue, as it means your emails aren't even making it past the initial connection phase.

For SaaS companies, your block bounce rate should ideally be zero. A rate of even sub-1% is a red flag. Any block bounces indicate that your sending reputation is compromised, potentially affecting all email traffic from your shared IP or domain. This can be caused by sending to spam traps, having too many invalid addresses, or triggering spam filters with problematic content. You can find more information about how your IP can get blocklisted in our guide how your email address ends up on a blacklist.

Monitoring various public and private blocklists (blacklists) is essential. If your IP or domain appears on one, it's critical to take immediate action to address the root cause and request delisting. This typically involves auditing your sending practices, cleaning your lists, and ensuring strong authentication protocols. We offer a blocklist checker to help identify if you are listed on any major ones.

The impact of high hard bounces

Sender reputation decline: Mailbox providers penalize senders with high hard bounce rates, leading to lower deliverability and potential blocklisting.
Blocklisting: Your IP or domain might be added to private or public blacklists, preventing your emails from reaching recipients.
Wasted resources: Sending emails that will never be delivered consumes bandwidth and affects reporting accuracy.

Beyond the numbers: achieving best-in-class deliverability

While metrics provide valuable insights, true best-in-class deliverability goes beyond just hitting target percentages. It's about implementing a holistic email program that prioritizes user engagement, list hygiene, and robust authentication. For SaaS companies sending on behalf of many clients, this also means diligently monitoring individual client sending practices to protect the overall sending reputation of your shared infrastructure.

We often see providers getting too caught up in trying to run their sending purely from a spreadsheet of numbers. While measurements are essential, they are inherently imperfect and should be used as directional indicators, not rigid rules. The most effective approach is to continually assess your performance against your own historical data and defined goals, rather than relying solely on generalized industry benchmarks that may not apply to your specific use case or email volume.

Prioritize practices that ensure genuine engagement and minimize risks. This includes implementing double opt-in for new subscribers, regularly cleaning your email lists to remove inactive or problematic addresses, and strictly adhering to email authentication standards such as SPF, DKIM, and DMARC. These foundational elements are far more impactful than chasing a specific percentage point in a report.

Focus on numbers only

Risk of misinterpretation: Numbers can be misleading if the underlying data definitions vary between providers or campaigns.
Ignores root causes: Chasing metrics without addressing list quality or authentication issues offers only temporary relief.

Focus on best practices

Sustainable improvement: Aims for long-term health by building strong foundational email practices.
Adaptability: Better equips your program to handle evolving deliverability challenges and mailbox provider requirements.

Final thoughts on email deliverability for SaaS

Achieving best-in-class email acceptance, hard bounce, and block bounce rates for a SaaS company means committing to ongoing vigilance and proactive management. It's about recognizing that deliverability is a dynamic process influenced by numerous factors, not just static metrics. By focusing on maintaining a clean email list, implementing robust authentication, and consistently monitoring your performance against your own baselines, you can ensure your emails consistently reach their intended recipients, supporting the success of both your product and your customers.

For SaaS providers who send on behalf of multiple clients, the responsibility is even greater. A holistic approach to sending practices across your entire user base is essential to protect your organizational sending reputation. This means not getting bogged down by generalized industry metrics but instead focusing on best current practices tailored to your specific infrastructure and client needs.

Ultimately, your email program's success is measured by the emails that land in the inbox and engage users, not just those that are initially accepted. By taking a comprehensive approach and understanding the nuances of these critical metrics, SaaS companies can build and maintain a strong foundation for email deliverability.

Views from the trenches

Best practices

Implement a double opt-in process for all new email sign-ups to ensure high-quality, engaged subscribers and prevent sending to invalid addresses.

Regularly scrub your email lists to remove inactive subscribers, hard bounces, and known invalid addresses to maintain list hygiene.

Monitor individual customer email metrics as a SaaS provider, as well as the overall sending reputation of your infrastructure.

Define your own consistent internal metrics for hard bounces and block bounces and measure against your historical performance and goals.

Focus on a holistic approach to sending practices across your entire user base, rather than getting solely focused on industry benchmarks.

Common pitfalls

Relying solely on external industry benchmarks without understanding their context or how different providers define metrics like 'hard bounce'.

Failing to immediately remove hard bounced email addresses from your mailing lists, which can severely damage sender reputation.

Neglecting to monitor block bounces (rejections due to blacklists), as even a sub-1% rate indicates a significant deliverability problem.

Treating deliverability as purely a 'metrics game' instead of focusing on fundamental best practices across your sending program.

Not recognizing that acceptance rate doesn't guarantee inbox placement; accepted emails can still end up in spam folders.

Expert tips

If you are a SaaS provider, each of your customers should aim for a high acceptance rate (~98-99%), a low bounce rate (~1% or less), and a very low complaint rate (~0.05%).

Block bounces should ideally be zero, but acceptably very low (sub 1%). Hard bounces may initially be 2-3% but should be under 1% consistently.

Deliverability is not just a metrics game; it's about implementing best practices across your entire sending program.

While industry-specific metrics can be marketing fluff due to varying definitions, measuring your own performance consistently is valuable.

Combine various tools and measurements to get the best composite view of your deliverability performance, even if individual measures are imperfect.

Expert view

Expert from Email Geeks says SaaS providers should aim for high email acceptance rates, around 98-99%, with low bounce rates (1% or less) and very low complaint rates (0.05%). They also noted that acceptance does not guarantee inbox placement, as emails can still be routed to spam.

May 13, 2020 - Email Geeks

Expert view

Expert from Email Geeks said that block bounces should be zero or at least very low (sub 1%), and hard bounces might be 2-3% for the first email to an address but should be under 1% on an ongoing basis.

May 13, 2020 - Email Geeks