A publishing client experienced a gradual decline in email deliverability over several months. There were no obvious infrastructure failures, bounce spikes, or increases in rejected messages, but inbox placement was deteriorating without a clear cause. Their open-rate data hadn’t flagged anything unusual either, though we had already cautioned them that open rates are not a reliable standalone indicator of deliverability.
The Problem: A Gradual Decline in Inbox Placement
The client had no clear explanation for the decline. Sending behavior, authentication setup, and infrastructure had not changed materially. Yet domain reputation was slipping, and inbox placement was following.
Investigating Sender Reputation and Infrastructure
We began by reviewing the signals most likely to explain a gradual reputation decline. Authentication records and sending infrastructure showed no material changes, so we shifted focus to sender reputation and list-quality signals.
What We Found
Google Postmaster Tools showed that domain reputation had drifted downward over approximately 12 weeks.
We then ran the client’s sending IPs through a multi-RBL check using real-time IP blocklists commonly used across anti-spam infrastructure. One of the IPs was listed on a blocklist associated with spam-trap activity.
That shifted the investigation toward list hygiene.
The Root Cause: Lack of an Email Sunset Policy
The client had never implemented a sunset policy. A sunset policy is a defined rule that suppresses persistently inactive subscribers from marketing sends after a set period of inactivity.
Their database contained addresses that had not opened or clicked any email in over two years. That created conditions in which recycled spam traps could remain on the mailing list undetected.
A recycled spam trap is a once-valid address that went dormant and has since been repurposed by a mailbox provider or anti-abuse organization for reputation monitoring purposes. Continuing to send to long-inactive addresses increases the risk of hitting these traps, which can contribute to blocklist listings and gradual sender-reputation problems.
In this case, the blocklist listing, the large inactive segment, and the gradual deterioration in Postmaster Tools all pointed to list hygiene as the primary issue, although the available reputation data could not establish a direct causal link.
Also Read: Why Your Emails Are Going to Spam (And How Actually to Fix It): A Technical Guide
How We Fixed It: Implementing List Hygiene and Re-engagement
We segmented subscribers who had been inactive for more than 180 days. That threshold was chosen based on the client’s typical sending cadence and normal engagement cycle for an audience receiving weekly newsletters; 180 days represented a meaningful period of sustained non-engagement.
Subscribers in that segment were entered into a re-engagement sequence, giving them a clear opportunity to confirm they still wanted to receive email. Those who did not respond were suppressed from future marketing sends.
Once the list cleanup was complete, we submitted a delisting request to the blocklist. We deliberately waited until after the suppression work was finished before making that request, so that the underlying behavior driving the listing had already changed.
Also Read: Case Study 1: SPF, DKIM, and DMARC Passed So Why Did Gmail Send the Newsletter to Spam?
The Result
Domain reputation returned to its previous classification within six weeks of completing the cleanup and delisting process.
This recovery validated our list-hygiene diagnosis: persistently inactive subscribers are a liability, not an asset.
What This Case Shows
For this client, the gradual reputation decline with no corresponding authentication or infrastructure failure ultimately pointed to list hygiene as the primary issue. A disciplined sunset policy and regular suppression of persistently inactive subscribers were the practical changes that stabilized sender reputation and inbox placement.
Gradual reputation problems without an obvious failure point are worth investigating from a list-quality perspective before assuming an infrastructure or authentication cause.
Also Read: Case Study 2: Email Deliverability Drop After Moving to a Dedicated IP
Shikhar Jauhari is an entrepreneur, journalist, and digital content strategist with expertise in SEO, WordPress, and online publishing. He is the founder and editor of WRI News, where he covers entertainment, finance, government schemes & lifestyle. With a strong focus on delivering accurate, engaging, and reader-first content, he combines editorial excellence with data-driven SEO strategies to create content.
Over the years, Shikhar has worked as a content writer, editor, website manager, SEO specialist, business analyst, and finance professional for media platforms, businesses, and digital agencies. His experience spans content management, business strategy, taxation, accounting, and digital marketing, enabling him to approach every project with both editorial insight and strategic thinking.
