The Science of Inbox Placement: Expert Tips from Tom Sather
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The Science of Inbox Placement: Expert Tips from Tom Sather

Published : July 26, 2023

Welcome to the ninth blog in our ‘Ask the Expert’ interview series, where we bring you industry experts to talk about outstanding practices in email marketing.


Tom Sather is an authority in email marketing with over two decades of experience. A former Senior Director of Marketing at the email intelligence company Return Path, Tom has been driving growth and establishing industry best practices. He was adjudged the Best Content Director at The Content Council Pearl Awards. As the founder of Email Lookout, Tom provides strategic consulting to optimize email marketing initiatives.

In this Q&A blog, Tom Sather talks about the key components that mailbox providers use to evaluate and determine inbox placement and offers actionable insights into them.

1. Could you tell us about your background, how you got interested in this subject, and the subsequent path that led you to specialize in decoding mailboxes?

My journey began in the early days of the Internet. I had worked at a few telecom and internet provider companies, and I was fascinated and excited by how the digital world was changing the way we communicate. This curiosity led me to a job at one of the world’s first email service providers, where I got a first-hand look at the challenges businesses face in reaching their audiences. I quickly realized that effective email delivery is an intricate puzzle with many pieces, one of which is understanding mailbox providers and spam filters. The more I delved into it, the more I was drawn to the complexity and importance of inbox placement. My passion for problem-solving and my interest in the digital communication sphere naturally led me to specialize in decoding mailbox providers.

2. What are the key components that mailbox providers use to evaluate and determine inbox placement? Could you provide insights into these metrics and their importance?

When it comes to what mailbox providers use to determine inbox placement, there are a few key components. They’re like the secret ingredients in a recipe that gets your emails delivered right into the inbox.

First, we have Sender Reputation. Imagine it as your email credit score. The better your reputation, the more likely your email will reach the recipient’s inbox. It’s influenced by factors such as email volume, bounce rate, and complaint rate. Then we have Engagement, which is all about how recipients interact with your emails. Are they opening them, replying to them, or ignoring them? All these matter.
The third is Content Relevance. Do your subject lines make sense? Is your email content valuable to the recipient? Even your email’s HTML structure matters. Lastly, we have List Hygiene.  Your email list is like a well-kept garden; you’ve got to regularly weed out inactive subscribers and keep it free from spam traps.

3. How do reputation metrics affect inbox placement? What strategies can marketers apply to build and maintain a positive sender reputation?

When we talk about reputation, it’s all about the beliefs or opinions formed based on past experiences or behavior. Let’s think of it in terms of a friend who always shows up on time – you’d probably trust that they’ll be punctual in the future, right? In the email world, it’s pretty similar. Email reputation is an opinion formed by mailbox providers about how trustworthy your emails are. This opinion is based on your prior sending behavior.

Those behaviors are like breadcrumbs that lead to your reputation. They include things like how many of your subscribers have marked your emails as spam, whether your email volumes are consistent or if they fluctuate wildly, and how many of your sent emails actually reach a valid address versus those that bounce or land in spam traps. These are all clues that mailbox providers use to form an opinion about your email behavior.

So, how can marketers build and maintain a strong reputation? It’s a bit like maintaining a healthy lifestyle – consistency is key.

First and foremost, you need to ensure that your emails are solicited. Sending unsolicited emails is a surefire way to damage your reputation. Next, aim for predictable and consistent email volumes. Erratic behavior can raise red flags with mailbox providers.

Keeping a low bounce rate and a low spam complaint rate are also crucial. This means you should keep your email list healthy and avoid sending emails to those who don’t want them.

And don’t forget authentication! Implementing authentication protocols like SPF, DKIM, and DMARC is akin to showing your ID at the door. It helps to validate that your emails are genuinely from you, adding a layer of trust and credibility to your emails.

Maintaining a strong email reputation is a marathon, not a sprint. It requires consistent good practices and responsive adjustments based on feedback. With these strategies in place, you’re more likely to land in the inbox rather than the spam folder.

4. What are the common challenges or obstacles businesses may face in achieving high inbox placement rates? How can they overcome these challenges and establish themselves as trusted senders?

Certainly, achieving high inbox placement rates can sometimes feel like an uphill battle, and businesses may face a number of challenges along the way. Here are some of the top obstacles businesses face and the solutions to achieve high inbox placement rates:

1. Poor Sender Reputation

If businesses have a history of sending emails that receive a high rate of complaints or get frequently marked as spam, this can harm their sender reputation. Mailbox providers might start diverting their emails to spam folders instead of the inbox.

Solution – Maintain good email practices. Send emails only to those who have opted in to receive them, be consistent in your sending volume and frequency, and actively manage your email list to remove invalid or unresponsive addresses.

2. Low Engagement Rates

Mailbox providers track how recipients interact with emails. If recipients rarely open or interact with the emails, or worse, delete them without reading, it could indicate to providers that the emails are not valued, potentially impacting inbox placement.

Solution – Increase your engagement rates by providing relevant, valuable content that is tailored to your audience’s interests. Also, ensure your subject lines are enticing and reflective of the email’s content to encourage opens.

3. Poor List Hygiene

A list filled with old, inactive, or non-responsive addresses can be a significant obstacle in achieving high inbox placement rates. These emails may bounce or get marked as spam, damaging sender reputation.

Solution – Regularly clean your email list. Remove bounced email addresses, and consider implementing a re-engagement campaign for inactive subscribers. Some businesses use a double opt-in process to ensure their list only includes active and interested subscribers.

4. Lack of Email Authentication

Without proper email authentication, mailbox providers might doubt the legitimacy of the emails, leading to them being classified as spam.

Solution – Implement authentication protocols like SPF, DKIM, and DMARC to verify your emails. These protocols help prove that your emails are genuinely from you, which adds to your credibility and increases the likelihood of your emails landing in the inbox.

Remember, successful email marketing is about building and maintaining trust, both with your recipients and with mailbox providers.

5. What strategies can brands implement to monitor and track their inbox placement rates? Are there any tools or services that can help analyze and improve inbox placement performance?

Monitoring and tracking inbox placement rates are an integral part of email marketing. Brands can employ several strategies and tools to stay on top of this:

1. Delivery Rate Monitoring

A basic way to start is by checking your delivery rates, i.e., the percentage of emails sent that were successfully delivered to the recipient’s server. High bounce rates can be a red flag indicating deliverability issues.

2. Open and Click-Through Rates

Keep an eye on your open and click-through rates. If you notice a significant dip, it might mean your emails aren’t reaching the inbox.

3. Feedback Loops

Many mailbox providers offer feedback loops where they will inform you when a recipient marks your email as spam. This service can help identify any major issues quickly.

4. Seed Testing

This involves sending your email to a list of ‘seed’ addresses managed on multiple mailbox providers. By monitoring whether these emails land in the inbox or spam folder, you can gauge the effectiveness of your inbox placement.

5. Engagement Analysis

Analyzing how recipients engage with your emails (e.g., opens, clicks, deletes, moves to different folders) can provide insights into how your emails are perceived, which affects inbox placement.

By leveraging these strategies and tools, brands can ensure they’re regularly monitoring their inbox placement rates, quickly identifying any potential issues, and implementing effective strategies to improve their performance.

6. Can you provide insights into the future of mailbox provider metrics and their impact on email deliverability? What advancements or changes can businesses expect in this area?

While I don’t have any specific insights on how mailbox providers will be tackling email spam and security in the future, I can imagine how the future of email deliverability will be reshaped with advancements in AI and other emerging technologies.

One innovative strategy could be Contextual Spam Analysis, where an AI system understands not just individual words but the entire context of an email to identify spam. In tandem, the introduction of a global Sender Reputation System could provide a shared database of email addresses and their spamming history, significantly enhancing trust in email communication.

One could also envision a Certified Email System using blockchain technology, requiring users to verify their emails on the blockchain before sending, which could drastically curtail mass spamming attempts.

As security measures advance, Multi-Factor Authentication for Emails could be implemented, making it increasingly challenging for spammers to automate their process. We might also see Advanced Image Recognition software being developed to detect spam hidden within visual content as well.

A pivotal strategy could be the use of AI to continually generate decoy accounts, commonly referred to as ‘spam traps.’ By generating a continuous stream of these decoy accounts, we can not only catch and flag spammers but also expose those senders who don’t adhere to good list hygiene practices. Since these AI-generated decoy accounts will be less predictable and harder to identify, senders can’t just remove them from their lists like they might with known spam trap addresses. This enhanced strategy could ensure that only those who truly prioritize consent and proper list maintenance can achieve high inbox placement rates, further promoting a healthier email ecosystem.

In conclusion, the future of mailbox provider metrics and email deliverability practices will be incredibly dynamic, especially with the growth of AI. Companies that stay ahead of these technological advancements and adapt their strategies will be in the best position to maintain high inbox placement rates and ensure effective message delivery.

7. How can businesses adapt to the evolving algorithms of mailbox providers and ensure a consistently high inbox placement rate?

Staying current with the evolving algorithms of mailbox providers is an essential strategy for businesses to maintain high inbox placement rates. Here’s how you can navigate this complex terrain:

1. Leverage AI-Powered Solutions

Artificial intelligence can help optimize email campaigns to ensure they reach the right inboxes at the right time. AI can learn from millions of user engagement touchpoints, providing insights to create highly effective campaigns.

2. Stay Informed with Data-Driven Insights

Utilize tools that provide performance metrics beyond traditional logs and summary counts. Having a comprehensive view of your email traffic, including metrics such as health score, engagement, and inbox placement, allows you to stay ahead of industry trends and adapt your strategies accordingly.

3. Maintain Consistent Sending Patterns

Consistency is key when it comes to sending volumes and frequencies. Sudden spikes in email sending can raise red flags with mailbox providers and negatively impact your inbox placement. Utilizing tools that help maintain consistent sending patterns can help avoid this.

4. Use Personalization and Segmentation

Segment your audience based on their interests, behavior or demographics, and personalize your emails accordingly. This can increase engagement rates, improve your sender reputation, and subsequently enhance inbox placement rates.

5. Test and Optimize

Regularly test different aspects of your emails, such as subject lines, content, or send times, and optimize based on the results. This iterative process can help improve your email performance and inbox placement rates.

Achieving high inbox placement rates is an ongoing process. It requires sending high-quality, relevant content and continuously optimizing your email practices. By staying informed, leveraging AI, and focusing on engagement, businesses can adapt to the evolving mailbox provider algorithms and maintain high deliverability.

8. What are some common myths or misconceptions that brands have regarding mailbox provider metrics and inbox placement?

There are a number of common myths and misconceptions that brands often have regarding mailbox provider metrics and inbox placement. Let’s address a few:

1. “More Emails, More Engagement”

Many brands believe that sending more emails will naturally lead to higher engagement. However, this can often lead to fatigue among subscribers and potentially higher unsubscribe rates and higher complaint rates. A focus on sending highly relevant and personalized emails to engaged subscribers is more effective than simply increasing email volume.

2. “All Spam Filters Work the Same”

Spam filters vary greatly between different mailbox providers, each with their own set of rules and criteria for what constitutes spam. What might pass through one provider’s filter might be flagged as spam by another. Understanding the nuances of each mailbox provider’s spam filtering algorithm is crucial for successful inbox placement.

3. “Inbox Placement Equals Delivery”

Many brands equate delivery with inbox placement, believing that if an email is delivered, it has reached the subscriber’s inbox. However, ‘delivered’ simply means the email has not bounced and has reached the recipient’s server. It could still end up in the spam or junk folder. Inbox placement rate, on the other hand, is the percentage of sent emails that actually land in the inbox.

4. “High Open Rates Guarantee Inbox Placement”

While open rates can be an indicator of email engagement, they don’t necessarily correlate with inbox placement. Emails can land in the spam folder and still be opened, particularly if the recipient frequently checks their spam folder.

5. “Negative Metrics Only Affect One Campaign”

Brands often believe that high bounce rates or spam complaints only affect the specific campaign associated with those metrics. In reality, these negative metrics can impact your overall sender reputation, affecting inbox placement for future campaigns.

By understanding and dispelling these myths, brands can more effectively navigate the complexities of mailbox provider metrics and improve their inbox placement strategies.

9. Can you share any success stories where businesses improved their inbox placement rates significantly? What were the key strategies or actions that led to those improvements?

You know, it’s funny how sometimes small changes can make a world of difference. Like this one startup I can recall. They were struggling to hit their sales targets because their sales invites just weren’t getting replies. We turned detective and dug into the issue, and found out that while their marketing emails were getting authenticated properly, their corporate emails from the same domain were getting left behind. After we fixed their authentication, it was like a door opened. Sales invitations started reaching prospects, and boom – their sales shot up.

Then there’s this other tale that’s worth sharing. Picture an employment recruiting company. They’re sending tons of emails to job seekers when suddenly, they hit a wall. All their emails to Gmail users were landing in spam, and then Gmail just started blocking their emails outright.

On inspecting, we found that the culprit was their email list. It was like an attic that hadn’t been cleaned for ages. If you were on their list 10 years ago, you were still there, probably getting emails you no longer wanted.

We decided to give that list a good spring cleaning. First off, we started a re-engagement campaign for all the inactive subscribers. Then we put in a rule: if a subscriber stayed inactive for a certain period, they were off the list. After these changes, it was like we gave the company a new lease of life. Gmail lifted the block, and our client saw their inbox placement rates bounce back above 90%.

So, you see, email marketing isn’t a set-it-and-forget-it kind of deal. It’s all about making the right tweaks and keeping everything in top shape. Sometimes, it’s the little things that can really turn the tide.

In the ever-evolving landscape of email marketing, understanding the key components that mailbox providers use to evaluate and determine inbox placement is crucial. Through this session, we have explored the vital metrics that influence inbox placement and the significance they hold in the success of email campaigns. By focusing on these, marketers can optimize inbox placement rates and forge meaningful connections with their audience.

Netcore is at the forefront of innovations that improve the key metrics for inbox placement. We are studying trends and forecasts, deploying AI and ML, and analyzing huge volumes of data to meet the highest achievable ROI in email ecosystems.  Connect with us to understand how you can benefit from our expertise and experience. We send over 20 billion emails a month on behalf of 6500+ businesses across 40 countries.

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