How to improve email deliverability and actually reach the B2B inbox

If your B2B emails land in the spam folder, even your best campaign still delivers nothing. Email deliverability is the degree to which your emails reach the recipient’s inbox instead of getting stuck in spam or blocked outright. According to EmailToolTester, 16.9% of B2B marketing emails never reach an inbox, and that is lost revenue and lost leads. In this article, you will learn how to fix that: through authentication (SPF, DKIM), list hygiene and a healthy sender reputation, so your campaigns actually convert.

What is email deliverability and why does it matter in B2B?

Deliverability is not about whether your email was sent, but about whether it arrived where it counts: in the inbox. An email can be technically “delivered” and still sit in the spam folder, where nobody ever opens it. For a B2B company, that is a commercial problem, not just a technical detail.

Do the math. If almost one in six emails never reaches the inbox, you are talking about a substantial share of your audience that simply does not see your message. In B2B, where you often work with a limited, carefully built list, every missed lead is one too many. Good marketing automation therefore lives or dies by the question of whether your emails arrive at all.

That is also why this is a question of what you steer on. At Customer Impact, we do not look at the number of emails sent, but at how many people your message actually reaches and how many of those generate a conversation or an inquiry. A list of ten thousand contacts that largely lands in spam is worth less than a smaller list that does arrive.

It helps to see deliverability as a series of hurdles that every email has to clear before it delivers anything. If your email trips over one of them, the rest of the chain no longer matters.

What deliverability rate should you aim for?

As a rule of thumb, you want to be above 95% deliverability. That is the level at which your campaigns reliably reach their audience. Mature platforms show it is achievable: Constant Contact, for example, reports a deliverability rate of around 97%.

If you are structurally below that, it is a warning signal. It means mailbox providers do not trust you, that your list is polluted, or that your content contains triggers that set off filters. The good news: those are all three things you can tackle yourself.

Do watch out for the right interpretation of your figures, though. A low deliverability combined with many unsubscribes points to a different problem than a low deliverability with few unsubscribes. For reference: GetResponse notes an average unsubscribe rate of around 0.15%. If you are well above that, you are probably sending too often or too irrelevantly, and over time that also chips away at your deliverability.

How do SPF and DKIM make your emails trusted?

Authentication is the foundation. Without the right settings, a mailbox provider like Gmail or Outlook does not know whether you really are who you claim to be, and in that case it chooses the safe option: your email in spam or rejected.

The three technical pillars:

• SPF (Sender Policy Framework): a record in your DNS that indicates which servers may send on behalf of your domain. It prevents others from abusing your domain.
• DKIM (DomainKeys Identified Mail): a digital signature that proves the email was not tampered with in transit and really comes from your domain.
• DMARC: a policy rule that brings SPF and DKIM together and tells providers what to do if an email fails the check.

For most Belgian B2B companies, this is a one-time setup that your IT partner or your email platform can arrange in half a day. Litmus lays out the broader principles of deliverability for anyone who wants to sharpen the technical side further. It is not ongoing work, but it is genuinely non-negotiable: without correct SPF and DKIM, even your best emails fail before they are read. Always start here, before you tinker with content or segmentation.

Why does a polluted list ruin your deliverability?

Your email list is not a static asset, it ages. People change jobs, email addresses are shut down and contacts lose interest. HubSpot estimates that the quality of an email list without maintenance declines by roughly 22.5% per year. If you do nothing, you are therefore sending to more and more dead addresses.

That is dangerous, because mailbox providers measure everything. Many bounces, few opens and many spam complaints tell Gmail and Outlook that your emails are unwanted, and they penalize your entire domain. A single polluted list can drag down the deliverability of your good contacts along with it.

What list hygiene means in practice:

• Remove or pause inactive contacts that have not opened anything for months, or first put them in a separate re-engagement flow.
• Clean up hard bounces immediately instead of continuing to email them.
• Work with double opt-in so that only real, interested addresses end up on your list.
• Send regularly, but not too often, so your list stays “warm” and active.

In B2B, it feels counterintuitive to delete contacts, because every name was hard-won. But a smaller, healthy list that arrives generates more leads than a large list that disappears into spam. If you want to go further here, also read how to automate a re-engagement campaign and how to segment your email list.

How do you build a healthy sender reputation?

Mailbox providers assign your domain, over time, a kind of trust score based on your behavior. If you consistently send relevant emails that people open and that generate few complaints, you build reputation. If you spam, that score drops and, with it, your deliverability.

A few principles that protect your reputation:

• Build volume gradually if you are using a new domain or a new platform. Suddenly sending ten thousand emails from an unknown domain looks like spam.
• Keep your spam complaints low by only emailing people who have subscribed and by making it easy to unsubscribe.
• Send relevant and segmented, so your opens and clicks stay healthy and providers see that people value your emails.
• Be consistent in sender name and domain, so recipients and filters recognize you.

Reputation is something you earn, not buy. That is precisely why setting up a drip campaign with relevant, spread-out content works better than a few big blasts: you train providers to trust you.

What role does your content play in spam filters?

Authentication and list hygiene bring your email to the gate, but your content helps determine whether it may pass through. Spam filters read your subject line, your layout and your text, and they also react to what recipients do with your email.

The subject line weighs more heavily than you think. According to FinancesOnline, 69% of people use the subject line as the main reason to mark an email as spam. A loud, overly salesy subject line therefore pushes you toward the spam folder yourself. And when people mark your email as spam, the provider learns from that, including for your next campaigns.

Also pay attention to the mobile display. OptinMonster reports that half of people delete an email that is not optimized for mobile. A deleted email counts as a negative signal for your reputation. In practice, this means:

• Write honest, relevant subject lines instead of clickbait.
• Avoid typical spam triggers (excessive capitals, “FREE!!!”, lots of exclamation marks).
• Make sure your email looks clean on mobile and loads quickly.
• Keep a healthy ratio between text and images.

Good content is therefore not only a conversion matter, it is also a deliverability matter. You can read more about the former in our email marketing tips.

When is working on deliverability not worth it?

Honest advice is part of the deal: not every company should put energy into this today. If you barely have a list or no sharp offer yet, deliverability is not your biggest problem. In that case, you are better off solving your lead problem and your offer first, because without relevant content and enough contacts there is little to optimize.

If you work with a small, red-hot network that you mostly email personally and one-on-one from your regular mailbox, a full deliverability approach is overkill. Getting SPF and DKIM in order remains smart, but list hygiene and reputation management only become truly relevant once you are structurally sending to larger groups.

In short: invest in deliverability at the moment email becomes a real channel for you, with regular campaigns to a list that is worth protecting. Not before.

Frequently asked questions about email deliverability

What is a good deliverability rate? Aim for at least 95% deliverability. Mature platforms reach around 97% (Constant Contact). If you are structurally lower, authentication, list quality or content are usually the cause.

Why do my emails end up in spam? The most common causes are missing authentication (no SPF or DKIM), a polluted list with many bounces and non-openers, a poor sender reputation, or content that triggers spam filters. Often multiple factors play together.

How often should I clean my email list? Regularly, because without maintenance list quality declines by roughly 22.5% per year (HubSpot). Remove or reactivate inactive contacts and clean up hard bounces immediately.

Does a larger email volume help my reach? Not if the extra emails land in spam. A smaller, healthy list that arrives generates more leads than a large list that providers distrust. Steer on reach and inquiries, not on volumes sent.

Do I have to set up SPF, DKIM and DMARC myself? It is a one-time technical setup that your email platform or IT partner can usually arrange quickly. It is the foundation of deliverability and non-negotiable for anyone who emails seriously.

Ready to make your emails actually arrive?

Deliverability is not a technical side project, it determines whether your email marketing generates leads and revenue or disappears into the void. The right authentication, a healthy list and a built-up reputation are together the difference between campaigns that convert and campaigns that nobody sees. We are a small team that moves fast and treats email for what it is: a channel to win qualified leads and customers, not to polish open rates.

Want to know where your deliverability stands today and what it will earn you to set it straight? Schedule your free intake.