Reducing email bounce rates: best practices for email campaigns

Reducing email bounce rates: best practices for email campaigns

Email bounce rates are a critical metric in understanding the effectiveness of your email campaigns and the quality of your database. Understanding and minimising bounce rates can significantly enhance deliverability and engagement of your campaigns. In this article we will explore email bounce rates, their impact, actionable tips, and benchmarking strategies to improve your email campaigns.

Understanding email bounce rates

What are bounce rates? Email bounce rates measure the percentage of emails that were not delivered to a recipient’s inboxes and were returned to the sender’s email server as undelivered.

Types of email bounces: Email bounces can be classified as hard bounces, indicating permanent delivery failures, or soft bounces, which are temporary delivery failures.

Hard bounces vs. soft bounces: Hard bounces occur when emails are sent to invalid or inactive email addresses, while soft bounces are due to temporary issues like full mailboxes.

What is email sender reputation? Email sender reputation is a key factor in email deliverability, influenced by factors such as bounce rates, complaints, and email content. Email sender reputation is a score assigned by Internet Service Providers (ISPs) that reflects the trustworthiness and reliability of an email sender. This score is determined by various factors, including the number of bounced emails, spam complaints, and engagement levels (opens, clicks, etc.).

Why are your emails bouncing?

Understanding the common causes of email bounces can help you take proactive steps to minimise them and ensure your emails reach their intended recipients. Regularly validating and cleaning your email list, as well as adhering to best practices for email sending, can significantly reduce bounce rates.

Top 10 reasons why emails bounce

1. Invalid email address:
Typographic Errors Simple typos in email addresses can lead to bounces. For example, “” instead of “”.
None existent Domain: If the domain part of the email address does not exist the email will bounce back. For instance, sending an email to “”.

2. Full mailbox
Recipient’s inbox is full: When the recipient’s mailbox has reached its storage limit, new emails cannot be delivered until some space is freed up.

3. Email server issues
Temporary server problems: The recipient’s email server might be down or experiencing issues, causing the email to bounce temporarily.
Permanent server shutdown: If the recipient’s email server has been permanently shut down, emails will bounce back permanently.

4. Spam filters
Triggered spam filters: Emails containing certain keywords, phrases, or formats may trigger spam filters, causing them to bounce or be marked as spam.
Blacklisted IP Addresses If your sending IP address is blacklisted emails sent from it might bounce.

5. Blocked email addresses
Recipient’s block list: If the recipient has blocked your email address or domain, your emails will bounce back.

6. Large email size
Exceeds size limit: Many email servers have a size limit for incoming emails. If your email, including attachments, exceeds this limit, it will bounce. Keep your email size under 100KB to not trigger spam filters.

7. Expired email address
Inactive accounts: If an email address is not used for a long period it may be deactivated or deleted by the email service provider, leading to bounces.

8. Misconfigured email settings
MX records issues: If the recipient’s domain has incorrect or misconfigured Mail Exchange records, emails sent to that domain will bounce.

9. Policy restrictions
Recipient’s email policy: Some organisations have strict email policies that block emails from unknown senders or certain domains.

10. Authentication failures
Lack of Authentication: Emails that are not properly authenticated (e.g., missing SPF, DKIM, or DMARC records) may be rejected by the recipient’s server.

Tips for reducing email bounce rates

Email bouncing may still happen regardless of whether the email address is correct, however you can take proactive steps to minimise the impact. By implementing the following strategies you can significantly reduce email bounce rates.

1. Update and clean your email list regularly: Remove inactive or invalid email addresses to maintain list health and improve engagement. Using an online database like Firmable, gives you access to accurate contact details, improving list hygiene and reducing the need for frequent cleansing.

2. Verify recipient email addresses: Ensure email addresses are accurate and up to date before sending emails. Within Firmable, you can also filter on email deliverability measures to limit your sends to those with a strong likelihood of accuracy for optimal delivery rates. Learn more on how to use email deliverability filters in Firmable.

3. Comply with the relevant spam regulators for the country you’re sending emails to: Learn more about the Spam Act from ACMA for Australia, and follow best practices for email marketing and communication to avoid triggering spam filters: This includes:

  • Getting consent: Ensure you have either express or inferred consent from recipients before adding them to your email list
  • Clearly identify yourself as the sender: Accurately identify your name or business name and include correct contact details too.
  • Provide opt-out options and making it easy to unsubscribe: Include clear and easy-to-find opt-out options in your emails allowing recipients to unsubscribe from future communications.

4. Avoid typos within your email context: Double-check email content including subject lines and message text to minimise the risk of typos that could lead to being identified as spam and bouncing.

5. Monitor mailbox status: Check the status of recipient mailboxes to prevent issues related to full mailboxes or exceeded storage limits.

6. Use clear subject lines: Avoid deceptive or misleading subject lines that may be flagged as spam or clearly communicate the purpose of the email.

7. Avoid spammy content: Refrain from using spam-like content such as excessive use of capital letters, multiple exclamation marks, and misleading claims.

8. Authenticate your emails: Implement email authentication protocols like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) to verify the legitimacy of your emails and increase deliverability rates.

9. Maintain DNS (Domain Name System) and domain integrity: Regularly monitor and address any DNS or domain-related issues to ensure smooth email delivery.

10. Optimise message size: Avoid sending emails with excessively large attachments or content that may exceed recipient server limits.

11. Rely on A/B split testing: Test different email elements to optimise engagement and minimise bounce rates.

12. Small targeted email campaigns: Personalise and segment your audience to allow for high value and targeted messages to reach the right audience and reduce your unsubscribes and increase engagement.

Benchmarking email bounce rates

What is a good bounce rate? A good bounce rate is typically around 2% or lower, but this can vary depending on factors such as industry and email list quality. For more details on email bounce rates and industry benchmarks, check out Campaign Monitor’s, ‘Ultimate Email Marketing Benchmarks for 2022: By Industry and Day’, article.

Benchmarking strategies

1. Analyse Industry averages: Compare your bounce rates with industry benchmarks to assess performance and identify areas for improvement.

2. Monitor trends over time: Track bounce rates over time to identify patterns and adjust email strategies accordingly.

3. Segment your database lists: Compare bounce rates between cold and warm database lists to understand engagement levels and tailor communication strategies.

Leveraging Firmable for email validation

In the realm of email marketing, ensuring the accuracy of recipient email addresses, especially when you are building a new database or cold outreach, is paramount to reducing bounce rates and maintaining deliverability.

Firmable offers two-tiered email verification of all its B2B data emails and allows businesses to proactively validate and clean their emails lists, resulting in reduced bounce rates, improved deliverability, and greater campaign success.

Firmable provides customers with an up-to-date B2B contact and company database platform that integrates into your CRM for seamless email marketing campaigning.


By understanding email bounce rates and implementing best practices as well as leveraging tools like Firmable for data and email validation, businesses can enhance email deliverability, engagement, and overall campaign success.

“Since using Firmable our new contact email bounce rates have dropped off by around 20-25%. We put this down to getting more accurate data coming through from Firmable” Margaret Foley, Chief Customer Officer, Simple Marketing Solutions.

Sign up now for a free 14 day trial and reduce your bounce rates:

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