Chapter 4
Engagement and sender reputation
Mailbox providers have opinions about every organization that sends email. Do you know if your reputation is good or bad? Find out why getting contacts to consistently engage with your emails is an effective way to be seen in a positive light.

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Road to the inbox: Navigating email deliverability in 2025
Why is email deliverability important?
Growing a healthy contact list
Measuring inbox placement
Engagement and sender reputation
Key findings on engagement and reputation
Email engagement: Sending the right signals
Understanding sender reputation
What impacts your sender reputation?
Three tactics to improve email engagement
Tackling technical email deliverability
Improving deliverability after the open
About this survey
PUBLISHED ON
Reliable deliverability is directly connected to a strong email marketing strategy. Your organization could have a flawless technical framework with solid email infrastructure and authentication. But if too many people on your list don’t want or care about your emails, you could still struggle with deliverability.
To support your reputation with mailbox providers, you need email marketing efforts that your contact list is ready and willing to engage with. Let’s find out why consistently getting good email engagement is a crucial part of reaching the inbox.
Table of contents
Why do people open, click, and unsubscribe?
Monitoring sender reputation
4 ways to use Google Postmaster Tools
1. A/B testing in email
2. Segmenting your email list
3. Personalizing email campaigns
Key findings on engagement and reputation
.%
of senders rate their understanding of their sender reputation an 8 out of 10 or higher.
%
of senders chose “increasing engagement” as the best way to improve sender reputation.
%
of consumers say they’re most likely to click on an email to claim a deal or use a coupon code.
%
of senders are not using any services to monitor their reputation with major mailbox providers.
Email engagement: Sending the right signals
In Chapter 3, we mentioned how there are both positive and negative engagement signals that affect email deliverability. Essentially, this means mailbox providers pay attention to how your contacts interact with what you send.
The more positive signals there are, the more likely it is that services such as Gmail and Outlook will filter your messages into the inbox. Too many negative signals, and those providers may assume your emails deserve to go to spam instead.
👍 Positive engagement signals | 👎 Negative engagement signals |
High open and click rates High read rates Scroll depth Replies and forwards Marking as “not spam” | Low open and click rates Deleting emails without reading Marking as spam High unsubscribe requests |
Mailbox providers want people to have a good experience using their email services. When your subscribers send signals that your emails are unwanted, unimportant, or annoying, mailbox providers may not wait for those users to unsubscribe on their own. Services like Gmail proactively ask users if they want to unsubscribe from a brand’s emails when people haven’t engaged in a long time.
Inboxes are already overcrowded. The best way to prove you deserve to be in the inbox is to respect your subscribers and deliver valuable emails that are anticipated, timely, and relevant. In other words, you need to maintain or increase email engagement.
Why do people open, click, and unsubscribe?
The path to email engagement, Sinch Mailjet’s separate survey of consumers, asked people what encourages them to engage with emails – from the time they subscribe to their decision to opt out.
Here’s how consumers rated the importance of four common tactics marketers use to make email subject lines more engaging.
.%
say recognizing the brand or sender name is very or somewhat important.
.%
say knowing content is personalized to their interests is very or somewhat important.
.%
say a discount or time-sensitive offer in the subject line is very or somewhat important.
.%
say seeing their name in the subject line is very or somewhat important.
Unsurprisingly, when consumers opt in for promotional emails, promotions are what they want and expect to receive. When asked to choose the top three reasons they click on emails, many people indicated they click on emails to take advantage of deals or learn more about products and offers mentioned in the campaign.
Out of the following options, when are you most likely to click on an email and visit a brand's website? (Respondents selected up to three)
These results indicate that familiarity with your brand, relevant promotional offers, and advanced email personalization are all effective ways to get your contact list to engage. However, it’s equally important to understand what prompts those negative signals.
Top 5 reasons why people unsubscribe:
Too many messages from the brand (19.8%)
No longer interested in the offers (17.9%)
Email content is irrelevant to me (17.3%)
Don’t remember subscribing (9.9%)
Inbox is too cluttered (9.7%)
If you want to keep contacts engaged with email, you’ll need to find the right balance between too many and too few communications. Too many emails and you annoy people, too few and they won’t remember signing up.
Above all, you’ve got to find a way to deliver what your subscribers want. If your emails are uninteresting, irrelevant, or considered nothing but clutter, you’ll eventually notice negative consequences on deliverability. That’s because mailbox providers are watching.
Get the full report on email engagement
Access all the insights from The path to email engagement. Download our free, ungated research report to learn much more about consumer preferences and opinions. Plus, get tips and advice from email marketing experts along the way. Start building a better inbox experience.
Understanding sender reputation
We’ve brought up “sender reputation” in previous chapters, but how well do you really know what it means to have a good sender reputation?
What is email sender reputation?
Your sender reputation is a score that mailbox providers assign to the domains and IP addresses from which you send emails. It’s based on email sending patterns and behaviors as well as the actions of recipients. Providers use sender reputation to decide whether emails should be filtered into spam, make it to the inbox, or get rejected from delivery.
When we asked senders to rate their understanding of their sender reputation on a scale of 0 to 10, 25.5% claimed to have a high understanding (8 to 10). More than 42% of senders rated their understanding of sender reputation in the middle (4 to 7) and 32% rated it low (0 to 3).
Using a scale of 0 - 10, rate how well you understand your sender reputation with services like Gmail, Outlook, and Yahoo.
Only around 25% of respondents feel confident about their understanding of sender reputation. So, what about the rest? Are there ways to learn more about how mailbox providers like Gmail and Yahoo view your email program?
Monitoring sender reputation
Some dedicated deliverability platforms provide reporting on sender reputation. That includes options like Mailgun Optimize’s Email Health Score as well as the Sender Score system, both of which provide an aggregate picture of sender reputation.
There are also free services from mailbox providers that offer insights into your reputation with those specific providers. Gmail has Google Postmaster Tools. Outlook has Microsoft’s Smart Network Data Services (SNDS), and Yahoo Mail/AOL has its Sender Hub.
Even though access to these reputation monitoring services is free, many senders aren’t using them. Our survey found almost 70% of respondents do not use any of these options to gain visibility into their sender reputation.
Which of the following services do you use to monitor your sender reputation?
The most popular option is Google Postmaster Tools with 28% using the service. That makes sense as Gmail is the world’s most popular mailbox provider.
You might assume that Postmaster Tools is a complex, technical service meant for system administrators to set up and use. However, these reputation monitoring services also provide valuable information for email marketers and small businesses.
4 ways to use Google Postmaster Tools
Once you have access to Postmaster Tools, there are several things you can look for as a marketer or business owner.
1. Check your overall reputation with Gmail
Postmaster Tools assesses your IP and domain reputation and gives both a score. This pertains specifically to Gmail, which more than 1.8 billion people use for email.
High: These senders have an excellent track record with Gmail. This means you’re following their guidelines and have a low spam complaint rate. Deliverability to Gmail accounts will be strong.
Medium: These senders are known to send mostly quality emails with occasional low volumes of spam. Most emails will reach the inbox.
Low: These senders are known to send significant volumes of spam. Most emails will be filtered into the spam folder.
Bad: These senders have a history of sending lots of spam. Their complaint rate is high enough that most emails will be rejected or flagged as spam.

Postmaster Tools shows domain reputation improving
2. Monitor your complaint rate with Gmail
While email analytics often show your overall spam complaint rate, Postmaster Tools provides a specific number based on how often Gmail users mark your messages as spam.
The service provides an aggregate spam rate, which is unlike other providers that use a traditional feedback loop (FBL). Outlook, Yahoo Mail, and AOL, for example, send more detailed notifications about individual spam complaints. Google’s FBL does allow users to track spam rates by campaign and customer.

Postmaster Tools shows spikes in spam complaints
The reporting you see here shows extreme spikes in spam complaints. By monitoring Postmaster Tools, this legitimate sender learned a bad actor was spoofing a subdomain and causing serious problems. See the full story on Reddit.
3. Get insights to inform email strategy
In addition to a reputation score and spam rates, Postmaster Tools offers other datapoints marketers can use to optimize their efforts. That includes:
Aggregate data on email engagement in Gmail.
Delivery errors explaining why emails are rejected, failed to deliver, or were suspected to be spam.
Whether your emails are passing or failing authentication protocols.
When you have deliverability challenges with Gmail, this information can often help you pinpoint problems and adjust.
4. Cross-team email program collaboration
Google Postmaster Tools and similar platforms can serve as a bridge between technical teams and marketers. It gives both sides a source of truth for understanding email deliverability.
Technical teams can focus on proper configuration for email security as well as IP and domain reputation. Marketers can gain deeper insights into what’s working and what may need to change to improve sender reputation.
“Mailbox providers like Gmail want you to do the right thing. They want senders to have all the information they can. The fact that so few organizations are using Google Postmaster Tools is sad. If you’re not checking all the information that’s available to you, then you’re missing out.”

Nick Schafer
Sr. Manager of Deliverability & Compliance, Sinch
What impacts your sender reputation?
There are many factors that impact your sender reputation with mailbox providers. Some involve technical details like DNS records. Others are influenced by what you send and how your contacts respond to emails. We asked survey participants to choose the three factors they believed would have the biggest impact on improving sender reputation. These were the top responses:
Improving list hygiene (34.5%)
Reducing spam complaints (28.3%)
Reducing bounce rates (26.8%)
The truth is, every one of the options found on the following chart can affect your reputation as an email sender. Yet some of the factors, like engagement, should get more attention.
What are the best ways to improve/repair your sender reputation with mailbox providers? (Respondents selected up to three)
Less than 15% of respondents chose increasing email engagement (14.7%) as a top factor for boosting sender reputation. However, with domain reputation playing an increasingly important role, that’s one of the best ways to show mailbox providers your emails should reach the inbox.
Many aspects of email are connected. So, when you focus on list hygiene, reducing spam complaints, A/B testing, or using segmentation and personalization, you’re also likely to increase email engagement in the process.
“Engagement is your lifeline to reputation as a sender. It is extremely important. If you think about what mailbox providers are doing, they want their users to get the emails they want to receive... And the way they do that is by looking at engagement.”

Nick Schafer
Sr. Manager of Deliverability & Compliance, Sinch
Three tactics to improve email engagement
Improving email engagement leads to improved deliverability. But it’s not the IT system administrators who have the creative strategies that prompt more people to open and click. That comes from the minds of marketers.
Of course, compelling subject lines and creative calls to action can only get you so far. The best ways to boost engagement involves more advanced email marketing tactics:
A/B testing
Segmentation
Personalization
These methods help you build more engaging, data-driven experiences for customers and contacts.
1. A/B testing in email
One of the best ways to understand how to build emails that your contacts find engaging is to experiment. A/B testing for email marketing involves sending two versions of an email to find out which performs best. A/B testing allows you to test specific elements in your email, like subject lines or calls to action (CTA), so you can define what makes a difference.
2. Segmenting your email list
List segmentation involves putting contacts into different groups so that you can deliver emails that are more meaningful and relevant. Instead of one email for everyone, you can send campaigns to people that have targeted messaging, specific product recommendations, and pertinent information.
You can also segment your list by how engaged contacts are. People who open and click often could receive emails more often, while less engaged subscribers are segmented on a separate list and only receive your most important campaigns.
3. Personalizing email campaigns
As stated earlier, our engagement survey found more than 80% of global consumers say personalized email content is important to them. However, consumers view name personalization in the subject line as less important.

A campaign with advanced email personalization
These two examples represent personalized emails from the same travel brand’s campaign. Both use the contact’s first name, which the company would collect during signup.
Each one also features a different destination and related imagery. That could be collected based on what web pages the contacts visited, or what they clicked on in a previous email campaign. The result is a more targeted and personalized message that is more relevant and more likely to get good engagement.
Segment and personalize with Sinch Mailjet
Sinch Mailjet makes it easy to deliver a more personalized email experience. Filter your contact list into segments based on subscriber data like location, age, language, and more. Then take things further with dynamic sections for advanced personalization in email campaigns.
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Chapter 3: Measuring inbox placement
Chapter 3
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Research report
Road to the inbox: Navigating email deliverability in 2025
Learn More

Chapter 1:
Why is email deliverability important?
Learn More

Chapter 2:
Growing a healthy contact list
Learn More

Chapter 3:
Measuring inbox placement
Learn More

Chapter 5:
Tackling technical email deliverability
Learn More

Chapter 6:
Improving deliverability after the open
Learn More

Chapter 7:
About this survey
Learn More