Deliverability: The impact of inbox placement

Nearly 9 out of 10 respondents in Sinch Mailgun’s survey feel that reaching the inbox is important to their organization. Those respondents include C-suite executives as well as VPs and director-level job roles. Among that group of business leaders, 52% described their ability to reach the inbox as extremely important.

While 43% of all survey participants believe their company’s email deliverability improved in the last year, around the same amount (42%) say it stayed the same.

Compared to results from Mailgun’s State of email deliverability 2025 research, there appear to be improvements in the adoption of important best practices. That’s especially true for email authentication as the latest sender requirements from Google, Yahoo, and Microsoft very likely prompted more organizations to implement and enforce the specification known as DMARC. 

In our 2025 report on the state of email deliverability, we slipped in a question asking participants to define what the delivery rate measures. Nearly 88% of senders failed to identify the correct definition of this metric. 51% thought the delivery rate measured the ability to reach the inbox, and 23% believed it was an overall deliverability metric. Both these answers are wrong.

There is no feasible way to look inside the mailboxes of every contact on your list to find out where each email landed. That’s why inbox placement tests exist. You can see the delivery rate, because it simply measures how many emails are accepted. This is done when a 250 OK SMTP response is returned from the receiving mail server. But again… an email could be accepted and then filtered into spam.

Finally, 8% of senders who aren’t using DMARC to support email authentication say they simply don’t see the value in doing so. But the truth is, despite the challenges, DMARC provides plenty of value.

DMARC adoption helps everyone involved in the email ecosystem. That goes for mailbox provides, customers and contacts, and senders like your company. Here’s why:

DMARC is the best way to keep phishing emails from reaching the inbox. So, the only people it hurts are the bad guys. When you set up DMARC, you’re doing your part to ensure email remains a useful customer communication channel. However, you also need to enforce DMARC to truly protect inboxes from phishing.

There are different ways to determine whether a contact is unengaged. Sinch Mailgun’s research revealed that 67% of senders with sunset policies use a time-based threshold. In other words, they sunset contacts after they don’t engage with emails for a certain number of weeks or months.

Another 29% will sunset contacts after they fail to engage with a specific number of email sends or campaigns. Most time-based strategies use a window of 30 to 90 days without engagement. Most campaign based sunset policies send at least 10 emails before an unengaged contact is removed. 

The reason senders adopt this practice is because your reputation as a sender is directly tied to where emails come from (AKA your domain and IP reputation). Marketing emails are more likely to be reported as spam. Cold sales emails could be even more likely to generate complaints. But people rarely complain about messages like order confirmations and password resets. If sales outreach, promotions, and important customer updates come from the same domain or IP, it increases the risk of transactional email getting filtered into spam.

Last year, Google made some changes to Postmaster Tools. Namely, the dashboard no longer includes a graph that visualizes IP and domain reputation with easy-to-understand colors representing High, Medium, Low, and Bad. Many people appreciated this simple snapshot.

But Alison Gootee thinks you shouldn’t sweat this update. She says sender reputation is much more nuanced than that, and it essentially boils down to two key factors:

Rather than worrying about colors, Alison says you should focus on doing things that truly support a stronger reputation.

Another trap is assuming that what you see in Google Postmaster Tools reflects the way other mailbox providers view you. That may not be the case, but you won’t know unless you’re checking out services like Microsoft SNDS and the Yahoo Sender Dashboard as well. 

When asked about meeting accessibility standards, only 36% of senders said they were concerned about sending accessible emails. 39% said they were not concerned while 25% were unsure.

Beyond the benefits of improved engagement and avoiding potential litigation or bad press, making your emails accessible is the right thing to do. Unfortunately, email industry research reflects our finding that most senders aren’t concerned.

The following statistics come from the Email Markup Consortium (EMC). They reflect in-depth research from the group’s Accessibility Report 2025, which examined the accessibility of more than 440,00 emails.  

Many of the ways you can improve email accessibility are easy to accomplish, and there’s no reason to ignore them. Not only will they make it easier for people with disabilities to engage with your emails, but they also make the inbox experience better for all of your customers and subscribers.

Find the right partner with a diverse deliverability toolkit, and you may not have to choose.