What typically causes high bounce rates and unengaged contact lists?

The primary cause is usually poor list quality, often due to purchased lists, outdated contacts, or a lack of double opt-in. Sending to these addresses results in hard bounces (invalid addresses) and low engagement, signaling to mailbox providers that your sender reputation is poor, leading to more emails being flagged as spam.

What's the single most impactful step for immediate improvement?

Start by identifying and suppressing (or removing) all purchased lists. Then, implement a strict list cleaning process to remove invalid and highly unengaged addresses. Prioritize explicit consent for all new subscribers through double opt-in.

Should different lines of business use separate email sending accounts or subdomains?

Yes, it's highly recommended. By separating mailstreams, you can prevent one line of business's poor sending practices from negatively affecting the deliverability of others within your organization.

Will DMARC monitoring reports give me insight into high bounce rates?

No, DMARC monitoring primarily focuses on email authentication, not direct deliverability issues related to list quality. While crucial for overall email security and preventing spoofing, it won't directly tell you why your specific list has high bounces. For that, you need your sending platform's bounce logs and engagement metrics.

What are the next steps after cleaning my email list?

Beyond cleaning, focus on email authentication (SPF, DKIM, DMARC), consistent sending volume, segmenting your list for targeted messaging, and creating engaging content that encourages opens and clicks. Continuously monitor your sender reputation using tools like Google Postmaster Tools .

What steps should I take to improve email deliverability with a large, unengaged contact list and high bounce rates? - Sender reputation - Email deliverability - Knowledge base

Dealing with a large, unengaged contact list and high bounce rates is a common challenge for email marketers, especially when inheriting an account with a complex history. I often encounter situations where sender reputation is damaged due to inconsistent sending practices, varying list quality, and a high volume of inactive subscribers. The key to improving email deliverability in such a scenario is a systematic and strategic approach, focusing on data cleanup, audience re-engagement, and adherence to best practices.

The immediate impact of a high bounce rate, particularly hard bounces, is a degraded sender reputation, which can lead to more emails landing in spam folders or being outright rejected. Unengaged contacts further compound this issue, as low open and click rates signal to mailbox providers that your content isn't relevant, flagging your emails as potentially unwanted. Addressing these issues requires a multi-faceted plan that prioritizes hygiene, authentication, and strategic sending.

Understanding the core issues

The first step in rehabilitating a troubled email program is to understand the extent of the damage and identify its root causes. With a substantial percentage of contacts never opening emails and high bounce rates, it is clear that list quality and engagement are major concerns. This requires a deep dive into your existing data and sending metrics.

Examine your current bounce rates and categorize them by type (hard vs. soft bounces) and by recipient domain. This granular data will help pinpoint where the biggest problems lie. A hard bounce indicates a permanent delivery failure, like an invalid email address, and these should be removed immediately. Soft bounces are temporary issues, but persistent soft bounces can also hurt your reputation and should be investigated. You should also analyze complaint rates, unsubscribe rates, and overall engagement metrics.

It is also critical to assess how contacts are being acquired across all lines of business. If purchased lists are being used, this is a major red flag and needs to stop immediately. Purchased lists are a primary source of high bounce rates, spam complaints, and placement on a blocklist (or blacklist). These lists often contain spam traps, which are designed to catch senders who don't follow best practices.

Prioritizing list hygiene

Once you have a clearer picture of the problem, the most impactful action you can take is to clean your email list. This involves identifying and removing invalid, unengaged, or problematic addresses. Given an 86% unengaged contact rate, a significant portion of your list is likely dormant or contains invalid addresses, contributing to your high bounce rates and poor sender reputation.

Risks of purchased lists

Sending to purchased or unverified lists is one of the quickest ways to damage your sender reputation. These lists often contain invalid addresses and spam traps, leading to high bounce rates and complaints. Mailbox providers interpret these signals as spammy behavior, which can result in your legitimate emails being blocked or sent to the junk folder.

Start by isolating the unengaged segments. For contacts that have never opened an email, or haven't engaged in a very long time (e.g., 6-12 months), it's advisable to suppress them from regular sending or attempt a specific re-engagement campaign. If they still don't respond, remove them. Continuously sending to disengaged users hurts your metrics and can even lead to your domain or IP being put on an email blacklist.

While DMARC monitoring is crucial for email authentication and security, it will not directly provide insights into the specific reasons for high bounce rates or unengagement on your existing list. DMARC primarily helps monitor SPF and DKIM alignment to prevent spoofing. Your sending platform's bounce logs and engagement metrics are the primary sources for this data.

Establishing a healthy sending foundation

Beyond cleaning your current list, you must implement practices that prevent future deliverability issues. This includes ensuring proper email authentication and developing a consistent, permission-based sending strategy.

Implementing double opt-in

Moving forward, implement a double opt-in process for all new subscribers. This verifies that email addresses are valid and that subscribers genuinely want to receive your communications. It significantly reduces the chances of acquiring invalid addresses and minimizes future bounce rates and spam complaints. It will also help improve overall engagement as the list will only contain highly interested recipients.

Example double opt-in confirmation messageText

Please confirm your subscription to our newsletter by clicking the link in the email we just sent you. Thank you for signing up!

Next, ensure your email domain is properly authenticated with SPF, DKIM, and DMARC. These protocols verify that your emails are legitimately coming from your domain, which is crucial for building and maintaining sender reputation. While DMARC reports might not diagnose bounce reasons directly, they provide vital feedback on your email authentication status and potential abuse of your domain.

Consider segmenting your large list based on engagement levels or other criteria. Instead of sending all emails to 2 million contacts, segment your list to target only engaged subscribers or those who have recently interacted. This practice can drastically improve your open and click rates, signaling positive engagement to mailbox providers and improving your sender reputation over time. You might also need to persuade management to remove unengaged subscribers.

Sustaining a positive reputation

After implementing initial cleanup and strategic sending, continuous monitoring is essential. This includes keeping a close eye on your bounce rates, complaint rates, and engagement metrics. Use tools like Google Postmaster Tools and

Microsoft SNDS (Smart Network Data Services) to track your domain's reputation with major mailbox providers. This data will show you how your sending reputation is evolving.

Old approach

Mass sending: Sending to the entire list, including unengaged contacts.
Poor data quality: Accepting all sign-ups without verification, potentially including purchased lists.
Reactive fixes: Only addressing issues after deliverability problems arise.

New approach

Segmentation: Targeting active and engaged segments for higher inbox placement.
Double opt-in: Ensuring all new subscribers are verified and genuinely interested.
Proactive monitoring: Regularly checking metrics and reputation to prevent issues.

If multiple lines of business are using the same sending account, consider separating their mailstreams. This can prevent one team's poor practices from negatively impacting the deliverability of others. For example, if one team insists on sending to purchased lists, isolating them to a separate subdomain or IP address can ringfence the damage and protect your main sending reputation.

Finally, focus on content relevance and consistency. Engaging content leads to higher open and click rates, which in turn signals positive engagement to mailbox providers. Consistent sending volume also helps maintain a stable reputation. Sudden spikes or drops in sending can be viewed with suspicion. This is a long-term project, but each small step contributes to significant improvement.

Views from the trenches

Best practices

Actively monitor your bounce logs to understand why emails are not being delivered and take corrective action.

Implement a double opt-in process for all new subscribers to ensure high-quality, engaged contacts.

Regularly clean your email list by removing unengaged subscribers and invalid addresses.

Common pitfalls

Sending to purchased or old, unverified email lists, which leads to high bounces and spam traps.

Ignoring feedback loops and bounce data, missing critical signals about deliverability issues.

Failing to segment lists, leading to sending irrelevant content to disengaged subscribers.

Expert tips

Use Google Postmaster Tools and Microsoft SNDS to monitor your domain's reputation with major mailbox providers.

Consider separating mailstreams for different lines of business to isolate any potential deliverability damage.

Engage in discussions with business line owners to understand their email usage and align on best practices.

Marketer view

Marketer from Email Geeks says to check the suppression or blocklist first and analyze bounce error codes to understand why certain mailbox providers are blocking emails.

2021-11-23 - Email Geeks

Marketer view

Marketer from Email Geeks says the number one priority is to stop bad data from entering the system before attempting to clean existing data.

2021-11-23 - Email Geeks

Rebuilding sender reputation and trust

Improving email deliverability with a large, unengaged contact list and high bounce rates is a significant undertaking that requires commitment and a methodical approach. It is not an overnight fix, but rather a multi-month journey involving aggressive list hygiene, strict adherence to permission-based sending, robust authentication, and continuous monitoring. By focusing on these core areas, you can systematically reduce your bounce rates, improve engagement, and rebuild a strong sender reputation, ensuring your legitimate emails consistently reach the inbox.