Are email senders experiencing a drop in Gmail Postmaster IP reputation in early July 2019 and what is the impact on delivery?
Michael Ko
Co-founder & CEO, Suped
Published 26 May 2025
Updated 19 Aug 2025
6 min read
In early July 2019, many email senders using Gmail Postmaster Tools observed a significant and unexpected drop in their IP reputation scores. Senders who had maintained a good or high reputation for extended periods suddenly saw their IP reputation fall into the bad segment. This widespread occurrence raised immediate concerns about potential impacts on email deliverability.
The situation led many to question if this was an actual reflection of diminished sending practices or perhaps a system anomaly. We investigated this pattern to understand its extent and, more importantly, its true effect on inbox placement. This article delves into the observations from that period and the broader implications for email deliverability and sender reputation.
The July 2019 anomaly in Gmail Postmaster Tools
During the first week of July 2019, specifically around July 2nd and 3rd, numerous senders reported seeing dramatic shifts in their IP reputation scores within Gmail Postmaster Tools. Historically stable IPs, used for consistent, compliant email programs, were suddenly flagged as low or bad. This was a point of immediate concern for many in the email community.
The pattern wasn't isolated to a few unlucky senders, but rather appeared to affect a broad spectrum of legitimate email programs. We saw reports from various sectors, including those with carefully nurtured lists and high engagement rates. The sudden, mass change suggested something systemic rather than individual sender errors. This prompted many to ask: is a bad IP reputation a false positive?
Some IPs saw a quick recovery, returning to high or medium status within a day or two, while others remained in the bad category for a bit longer. This fluctuation made it difficult for senders to accurately gauge their standing and predict deliverability outcomes. The inconsistency itself was a challenge.
This period highlighted the dynamic nature of IP reputation within email deliverability. While IP reputation is a critical factor, it's just one piece of a much larger puzzle. It underscored the need for senders to not solely rely on a single metric, even one provided by a major mailbox provider like Gmail.
Discrepancy between IP reputation and actual delivery
Despite the alarming drops in IP reputation in Gmail Postmaster Tools, a notable trend emerged: most senders reported no discernible impact on their actual email delivery, inbox placement, or even critical metrics like open and click rates. This was a crucial finding, suggesting that the observed IP reputation shifts might have been a temporary reporting anomaly rather than an accurate reflection of a systemic deliverability issue.
For many, their domain reputation, another key metric in Postmaster Tools, remained stable or even improved during this period. This stark contrast between IP and domain reputation reinforced the idea that Gmail's internal filtering algorithms likely rely on a complex interplay of signals, with domain reputation often holding more weight for established, legitimate senders. It also implies that IP reputation with stable open rates can be tricky to interpret.
Observed IP reputation
Postmaster tools: Sudden and widespread drop from 'High' to 'Bad' or 'Low' for many sending IPs.
Inbox placement: No significant decrease reported to Gmail inboxes.
Engagement rates: Open and click-through rates remained stable for most senders.
Domain reputation: Generally unaffected, remaining 'High' or 'Good' during the period.
This event underscored a critical lesson: while Google Postmaster Tools provides valuable insights, it should be interpreted in conjunction with other deliverability metrics. A temporary blip in one metric, especially IP reputation, doesn't necessarily mean your emails are going to spam if other indicators like domain reputation and engagement remain strong. It could simply be a recalibration or a transient anomaly in their reporting system.
Understanding Gmail's reputation signals
Gmail, like other major mailbox providers, uses a sophisticated set of signals to determine inbox placement. IP reputation is indeed one factor, but it’s complemented by many others. This includes domain reputation, sender authentication (SPF, DKIM, DMARC), content quality, and crucially, user engagement.
A high complaint rate or a high percentage of emails marked as spam will significantly impact your sender reputation, regardless of a temporary IP reputation dip. Similarly, inconsistent sending patterns, where volumes fluctuate wildly, can also trigger reputation flags. We often see this when senders rapidly increase or decrease their email volume.
Maintaining a strong sender reputation
Monitor actively: Regularly check Google Postmaster Tools for both IP and domain reputation, but look for consistent trends, not just momentary blips.
Authenticate properly: Ensure your emails are correctly signed with SPF, DKIM, and DMARC.
Maintain engagement: Send to active subscribers, remove disengaged users, and avoid sending to old or unverified lists.
Content quality: Avoid spammy keywords, excessive links, or overly promotional language that might trigger filters.
Ultimately, the best defense against deliverability challenges, including those indicated by a drop in IP reputation, is to focus on a holistic approach to email hygiene and sender best practices. This comprehensive strategy ensures that even if one metric experiences a temporary blip, your overall email program remains robust and trustworthy in the eyes of mailbox providers.
What to do when you see a sudden drop
The early July 2019 event in Gmail Postmaster Tools served as a valuable case study. It demonstrated that a drop in IP reputation, while alarming, doesn't always translate into a corresponding decline in email delivery. The key takeaway was to avoid panic and instead, adopt a data-driven approach.
When you observe such fluctuations, it's crucial to look beyond a single metric. Check your domain reputation, spam complaint rates, and critically, your engagement metrics like opens and clicks. If these remain stable, the IP reputation drop might be a temporary reporting quirk or a minor adjustment in Gmail Postmaster Tools.
Furthermore, ensuring your email program adheres to best practices remains paramount. This includes maintaining clean lists, sending relevant content, and having proper email authentication in place. These fundamental practices build a strong, resilient sender reputation that can withstand minor shifts in isolated metrics, ensuring your messages continue to reach the inbox.
Views from the trenches
Best practices
Always monitor a range of deliverability metrics, not just IP reputation alone.
Maintain consistent sending volumes and patterns to build stable trust with ISPs.
Focus on strong engagement metrics, as they are key indicators of sender health.
Implement and monitor DMARC to protect your domain and gain insight into email authentication.
Common pitfalls
Overreacting to temporary blips in Postmaster Tools without checking other data points.
Neglecting domain reputation in favor of solely focusing on IP reputation.
Not regularly cleaning your email lists, which can lead to higher bounce and complaint rates.
Failing to maintain proper email authentication (SPF, DKIM, DMARC) for your sending domains.
Expert tips
Understand that Gmail's internal reputation system is multifaceted, and Postmaster Tools offers a simplified view.
Temporary IP reputation drops can sometimes be due to internal system recalibrations by mailbox providers.
Leverage DMARC reports to get granular data on authentication failures and potential abuse, complementing Postmaster Tools.
Consider how changes in email content or sending frequency might correlate with reputation shifts, even if minor.
Marketer view
Marketer from Email Geeks says they were seeing the same thing, but their IP reputation was already showing signs of improvement.
July 3, 2019 - Email Geeks
Marketer view
Marketer from Email Geeks says they saw a red blip on July 2nd for IP reputation, which turned green by the 3rd, and their domain reputation remained good.
Postmaster tools: Sudden and widespread drop from 'High' to 'Bad' or 'Low' for many sending IPs.
