Should I be concerned about a temporary drop in Sender Score during IP warming?

While a drop can seem concerning, it's often not a major issue during IP warming if your other key metrics (opens, clicks, complaints, bounces) remain healthy. Sender Score provides a limited view and doesn't account for all ISP internal systems, especially those of major providers like Google and Yahoo.

What metrics are more important than Sender Score during IP warming?

Focus primarily on your internal engagement metrics like open rates, click-through rates, and, crucially, low spam complaint and bounce rates. These metrics directly reflect how recipients and ISPs are reacting to your emails.

Why might Sender Score fluctuate on a new IP during warming?

New IPs have no prior reputation, so initial scores can fluctuate as data is gathered. Also, Sender Score doesn't integrate data from all ISPs, meaning a dip might just reflect a segment of the email ecosystem, not your overall standing. Small fluctuations are normal as your volume ramps up.

What should I do if my Sender Score drops during IP warming?

If your other metrics are stable, you should continue your planned warming schedule. However, if you see significant increases in spam complaints or bounces, consider pausing your ramp-up, reviewing your list hygiene, and troubleshooting your sending practices .

Is a drop in Sender Score a concern for email deliverability during IP warming? - Sender reputation - Email deliverability - Knowledge base

Embarking on IP warming is a critical step to ensure your emails reliably reach the inbox. It's a gradual process designed to build a positive sender reputation with internet service providers (ISPs). When you're in the midst of this, meticulously monitoring various metrics becomes second nature. It's quite common to scrutinize everything, and sometimes, a metric like your Sender Score might show a dip.

I often hear concerns from senders who, like one email marketer recently, notice their Sender Score dropping from a high 99 to an 87 during warming, even when their internal metrics for spam, unsubscribes, and bounces remain stable. Their IP address also remains clear of any blacklists (or blocklists). This situation raises a very valid question: Is a drop in Sender Score truly a concern for email deliverability during IP warming?

Understanding sender score and IP warming

Sender Score, provided by Validity, is an email sender reputation metric that ranges from 0 to 100. It's often likened to a credit score for your sending IP address, aiming to provide an indication of your email program's health. A higher score theoretically suggests better trustworthiness in the eyes of mailbox providers.

During IP warming, the primary goal is to establish a positive reputation. This means gradually increasing your sending volume to show ISPs that you are a legitimate sender with engaged recipients. ISPs (like

Google or

Outlook) observe your sending behavior, including bounce rates, spam complaints, and engagement. They build an internal reputation profile for your IP and domain.

While Sender Score can be a useful, albeit limited, indicator, it's crucial to understand its context within the broader landscape of email deliverability. During IP warming, unexpected fluctuations in this score can occur for various reasons that don't always signify a major problem.

Metric	Description	Primary use during warming
Sender Score	A reputation metric from 0-100 for your IP address. Based on various factors, but data sources are not fully transparent.	A general guide, but don't rely on it exclusively due to its limited data. Can indicate broad trends.
Internal ESP metrics	Data reported by your Email Service Provider, including open rates, click-through rates, bounces, and complaints.	Crucial for understanding real-time recipient behavior and ISP feedback. Direct impact on deliverability.

As the table shows, while Sender Score provides a snapshot, it's your actual engagement and deliverability performance, as reported by your ESP, that truly reflects your standing with major mailbox providers. This is especially true when you're working to transfer email reputation during the warming phase.

Why sender score might drop during IP warming

A new IP address starts with no inherent reputation. During the initial stages of warming, ISPs are observing your sending patterns. A drop in Sender Score from a very high number (like 99) to a slightly lower, but still good, number (like 87) can sometimes be a statistical anomaly or reflect the score adjusting as more data points are collected from diverse recipient domains.

It’s also important to remember that Sender Score does not capture the full universe of email traffic. Major players like

Yahoo and Google, for instance, primarily use their own internal reputation systems, which are not directly reflected in a public Sender Score. Therefore, a dip in this specific score might not accurately represent your standing with these large mailbox providers.

Common expectations

Consistent rise: You expect your Sender Score to only increase during warming as your reputation improves.
Total reflection: You believe Sender Score provides a comprehensive view of your overall email deliverability.

Reality during IP warming

Initial fluctuations: New IPs can see scores fluctuate, especially as they begin sending to diverse audiences.
Limited scope: Sender Score aggregates data from a subset of ISPs and doesn't include all major players, making it an incomplete picture.

If your other key metrics (opens, clicks, complaints, unsubscribes) remain healthy and your IP isn't listed on any significant email blocklists, then a slight drop in Sender Score is likely not an immediate cause for alarm. It's more of a data point to observe, rather than a definitive sign of deliverability issues.

Key metrics to monitor instead of sender score

Instead of fixating solely on Sender Score, prioritize the metrics that directly reflect your deliverability and sender reputation with ISPs. These are your true indicators of performance:

Open rates: Are they consistent or declining across major ISPs? This is a strong signal of inbox placement.
Click-through rates: Indicates engagement with your content once emails hit the inbox.
Spam complaints: Any increase here is a red flag. Mailbox providers heavily penalize high complaint rates.
Bounce rates: Especially hard bounces, indicate issues with your list hygiene.
Unsubscribe rates: While not as severe as complaints, a rising trend suggests recipient fatigue or irrelevance.

Critical metrics for IP warming success

Focus on the data your Email Service Provider (ESP) provides directly, combined with feedback loop data (if available). These give you a real-time, accurate picture of how mailbox providers are perceiving your email volume and quality. If these core metrics are stable or improving, especially during your domain warming phase, it's a strong sign that your warming is progressing well.

Regularly monitoring these direct engagement and feedback metrics will give you a far more actionable understanding of your deliverability performance than an external aggregated score like Sender Score alone. If you see significant dips in open rates or spikes in spam complaints, then it's time to investigate further, perhaps by reviewing your list quality or content.

Actions to take if deliverability concerns persist

If you are concerned about a drop in Sender Score or any deliverability metric, here are some actionable steps to ensure your email program remains healthy:

Segment your audience: During warming, continue to send to your most engaged subscribers. An email marketer recently mentioned they only send to those who have engaged in the last 30 days, which is an excellent strategy.
Monitor blocklists (blacklists): Regularly check if your IP address has been listed on any significant public or private blacklists (or blocklists). A listing here would be a much greater concern than a minor Sender Score fluctuation.
Review content and frequency: Ensure your email content is relevant and not triggering spam filters. Maintain a consistent sending frequency throughout the warming period.
Check your DNS records: Make sure your email authentication records like SPF, DKIM, and DMARC are correctly configured and aligned.
Consult your ESP: Your Email Service Provider has the most granular data on your sending performance and can provide insights into specific ISP responses.

Remember, the goal of IP warming is to build a solid reputation that leads to consistent inbox placement. If your core deliverability metrics remain strong, a fluctuating Sender Score is usually not an urgent warning sign. Continue to focus on sending desired emails to engaged subscribers, and your deliverability should remain on track.

Final thoughts on sender score and IP warming

In conclusion, while a drop in Sender Score during IP warming can be unsettling, it is often not a critical concern for overall email deliverability. This is particularly true if your core metrics, such as open rates, spam complaints, unsubscribes, and bounce rates, remain healthy and stable.

Sender Score, while a helpful guide, provides a limited view and does not encompass all the factors ISPs consider. Trust your internal engagement data and direct feedback loops as primary indicators of your IP warming progress and deliverability health. Consistent monitoring and adherence to best practices will ensure your emails continue to reach the inbox effectively.

Views from the trenches

Best practices

Monitor your internal engagement metrics (opens, clicks, complaints) very closely. These are your true north stars during IP warming.

Segment your audience strictly during warming, only sending to your most engaged subscribers to build positive reputation.

Regularly check your IP against major blocklists, as these are more indicative of severe deliverability issues.

Maintain a consistent sending volume and schedule as outlined in your IP warming plan to avoid reputation shocks.

Ensure all your email authentication protocols (SPF, DKIM, DMARC) are correctly configured and aligned for your sending domain.

Common pitfalls

Over-relying on Sender Score as the sole indicator of deliverability success or failure, especially during the dynamic warming phase.

Panicking over minor fluctuations in external reputation scores without validating against internal performance data.

Increasing sending volume too quickly or inconsistently, which can trigger spam filters and damage reputation.

Neglecting to remove unengaged or inactive subscribers from your warming lists, leading to poor engagement signals.

Ignoring feedback loop data from major ISPs, which provides direct insights into recipient complaints.

Expert tips

External reputation scores are often backward-looking and don't always reflect real-time changes or all ISP behaviors.

Many large mailbox providers, like Google and Yahoo, rely on proprietary internal reputation systems not publicly visible.

A mixed B2B and B2C sending profile can introduce unique reputation challenges across smaller, niche recipient domains.

Focus on the actual recipient experience and the signals they send, such as opens, clicks, and complaint rates.

Treat Sender Score as one data point among many, not the definitive word on your deliverability.

Expert view

Expert from Email Geeks says they would trust organic data over Sender Score and to keep an eye on any changes in organic stats, but understand that Sender Score is very limited and not a full-picture assessment of deliverability reputation.

2024-07-15 - Email Geeks

Expert view

Expert from Email Geeks says they wouldn't pull the alarm yet and to be aware and watch for other measurable problems, but it's not enough of a data point on its own to be sure something is wrong.

2024-07-15 - Email Geeks