What tools and methods can I use to level up deliverability monitoring?
Matthew Whittaker
Co-founder & CTO, Suped
Published 15 Jul 2025
Updated 16 Aug 2025
7 min read
Achieving excellent email deliverability is a constant challenge for anyone sending emails, whether for marketing, transactional, or operational purposes. It is not enough to simply send emails and hope they land in the inbox. Proactive monitoring is crucial to ensure your messages reach their intended recipients and avoid spam folders or being blocked entirely.
Without robust deliverability monitoring, you are operating blind. You might be experiencing high bounce rates, low engagement, or even outright blocks without realizing the underlying issues. Understanding where your emails are landing and why is the first step toward improving your email program's performance.
This guide will walk you through various tools and methods that can help you level up your deliverability monitoring, ensuring your email program remains healthy and effective.
Leveraging ESP reporting for deliverability insights
A fundamental aspect of deliverability monitoring begins with the data you already have. Your own Email Service Provider (ESP) typically offers valuable reporting on key metrics. Paying close attention to these indicators can provide immediate insights into your email program's health.
I always start by analyzing bounce rates, open rates, click-through rates, and unsubscribe rates. Spikes in hard bounces often point to list hygiene issues, while a sudden drop in open rates for specific domains might indicate a reputation problem or a new filtering challenge at a particular mailbox provider. Tracking these trends over time, segmented by domain, is critical for identifying emerging issues. This internal monitoring is one of the essential tools and practices for email deliverability.
Leveraging your ESP's built-in reporting can also help you understand user engagement patterns. Consistent low engagement from certain segments or email addresses can signal that those recipients are not interested, which can negatively impact your sender reputation over time. Regularly cleaning your list and removing inactive subscribers is a vital practice informed by these metrics.
Monitor Bounce Rates: High rates suggest problems with list quality or recipient servers.
Track Open Rates: Sudden declines can indicate filtering issues or content problems.
Review Complaint Rates: High complaints are a strong indicator of unwanted mail and will damage your reputation.
Monitoring sender reputation with postmaster tools
Beyond your ESP's internal reporting, monitoring your sender reputation directly with mailbox providers is indispensable. Mailbox providers like Google and Yahoo (and AOL) offer free Postmaster Tools that provide critical data on your sending reputation, spam rates, and DMARC authentication. I regularly check these dashboards to understand how my sending domains and IPs are perceived.
These tools offer an unfiltered view of your deliverability directly from the source. For example, Google Postmaster Tools provides metrics like IP reputation, domain reputation, spam rate, and authentication errors (SPF, DKIM, DMARC). Yahoo's Complaint Feedback Loop is also crucial for understanding user complaints. If you want to dive deeper into understanding your domain reputation, these tools are a must-use.
Monitoring your sender reputation through these first-party tools helps identify potential issues before they escalate into major deliverability problems. Regularly checking these dashboards, ideally daily or weekly, allows for quick detection of drops in reputation scores or increases in spam rates, enabling prompt corrective action.
Tips for improving reputation
Maintain List Hygiene: Regularly clean your email list to remove inactive or invalid addresses to prevent bounces and spam trap hits.
Implement Double Opt-in: This ensures subscribers genuinely want your emails, reducing complaints and improving engagement.
Provide Easy Unsubscribe: A clear unsubscribe link helps avoid spam complaints from users who no longer wish to receive your emails.
Proactive testing and blocklist vigilance
To get a complete picture of your email deliverability, you need to go beyond reputation scores and actively test where your emails are landing. Inbox placement testing, often done through seed lists, allows you to send emails to a diverse set of email addresses hosted by various mailbox providers and see if they land in the inbox, spam folder, or are blocked.
Another crucial aspect is continuous blocklist monitoring. Being listed on a major email blacklist (or blocklist) can severely impact your deliverability. These lists are used by mailbox providers to identify and block mail from suspected spammers. Regularly checking various blocklists, both public and private, ensures you are aware of any listings promptly so you can take action for removal. My team uses a dedicated blocklist checker regularly.
Combining inbox placement testing with blocklist monitoring offers a comprehensive view of how your emails are being received across the ecosystem. This proactive approach helps you identify deliverability issues, whether they are due to content, reputation, or specific blocklist listings, allowing for timely intervention and strategy adjustments.
Inbox placement testing
Method: Send emails to a set of seed addresses (test accounts) at various mailbox providers.
Benefit: Provides a snapshot of where your emails are landing, e.g., inbox, spam folder, or blocked. This helps to monitor email deliverability.
Tools: Specialized services that provide seed lists and reporting.
Blocklist monitoring
Method: Regularly check if your sending IP addresses or domains are listed on email blocklists (or blacklists).
Benefit: Immediate alerts if your sender reputation is severely damaged, allowing for swift de-listing requests. This helps you understand what happens when your domain is blocklisted.
Tools: Online blocklist checkers that query multiple DNS-based blocklists (DNSBLs).
Advanced authentication and feedback loops
Email authentication protocols like SPF, DKIM, and DMARC are no longer optional, they are fundamental for deliverability. Monitoring their proper implementation and alignment is a critical aspect of leveling up your monitoring efforts. DMARC, in particular, provides valuable reports that show you which emails are passing or failing authentication checks, and why.
By analyzing DMARC reports, you gain insight into sending sources you might not even be aware of, helping to prevent unauthorized use of your domain for spoofing or phishing. These reports are XML files that can be complex to parse manually, so using a DMARC monitoring service is highly recommended for actionable insights. You can read more in our simple guide to DMARC, SPF, and DKIM.
Feedback Loops (FBLs) are another critical component. These programs, offered by major mailbox providers, notify you when a recipient marks your email as spam. This direct feedback is invaluable for identifying campaigns or list segments that are generating high complaints, allowing you to quickly adjust your sending practices and remove problematic addresses from your lists. This helps to proactively monitor spam rates and identify issues.
To effectively level up your deliverability monitoring, you need a multi-faceted approach. This includes diligently reviewing your ESP's internal metrics, leveraging free tools from mailbox providers, performing proactive inbox placement tests, and implementing robust email authentication protocols like DMARC.
The goal is not just to react to problems, but to anticipate and prevent them. By combining these tools and methods, you create a comprehensive monitoring system that provides deep insights into your email program's performance and allows for timely adjustments. This comprehensive approach is key to ensuring your emails consistently reach the inbox.
Remember, email deliverability is an ongoing process that requires continuous attention and adaptation. With the right tools and a disciplined monitoring strategy, you can significantly improve your inbox placement rates and maximize the effectiveness of your email communications.
Views from the trenches
Best practices
Actively analyze your ESP's internal reports, focusing on bounces, opens, clicks, and complaints across different domains.
Use Google Postmaster Tools and similar ISP dashboards to directly monitor your domain and IP reputation.
Regularly perform inbox placement tests using diverse seed lists to identify filtering issues at various mailbox providers.
Implement and monitor DMARC reports to detect authentication failures and unauthorized sending activity.
Common pitfalls
Relying solely on ESP reported delivery rates, which often don't account for spam folder placement.
Ignoring feedback loops or not acting on spam complaints, which can severely damage sender reputation.
Failing to monitor blocklists, leading to widespread email blocks without immediate awareness.
Not configuring or monitoring email authentication protocols (SPF, DKIM, DMARC) properly, causing emails to fail verification.
Expert tips
Set up alerts for significant drops in engagement or increases in bounce rates to react quickly to deliverability issues.
Segment your audience and analyze deliverability by segment to pinpoint specific issues.
Continuously test different email content and sending patterns to optimize inbox placement.
Engage with the email deliverability community to stay updated on best practices and changes in filtering algorithms.
Marketer view
Marketer from Email Geeks says that your own baseline trending, including bounces, opens, clicks, and opt-outs by domain, should be a key part of your email program.
2022-10-10 - Email Geeks
Marketer view
Marketer from Email Geeks says that Kickbox provides a comprehensive deliverability tool suite for monitoring.
