What Percentage of B2B Marketing Emails Never Reach the Inbox in 2025?

A message that never reaches the inbox might as well not exist. Some addresses are invalid and bounce, some servers reject mail when they glitch, and a lot of messages land in spam folders that few people check. In 2025, Mailtrap reports an average inbox placement rate of about 85%. That means around 15% of B2B email marketing emails never reach the inbox, or about 15 out of every 100 you send.

TL;DR

• About 15% of B2B email marketing emails don’t land in the inbox.

• What is the email deliverability best practice?: keep your email lists clean, authenticate your domain with SPF, DKIM, and DMARC, and re-verify quarterly.

Year-by-Year Inbox Placement

What the 15% Miss Rate Means for B2B Email Deliverability

The 15% represents messages that never reach a real inbox. They’re either rejected at the server level, because the address is invalid, or land in spam where people rarely see them.

The pattern has remained constant for the last several years:

• 2022: ~15.8% missed

• 2023: ~14% missed

• 2024: ~16.8% missed

• 2025: ~15% missed

So even as filters improve and senders strengthen authentication, about one in six B2B emails still fails to reach the inbox.

Why Emails Fail Deliverability or Land in Spam

1. Authentication gaps. Missing or misaligned SPF, DKIM, or DMARC records are still a leading cause of rejection or spam placement.

   a. SPF, DKIM, and DMARC are email authentication methods that confirm who sent a message and whether it was changed. SPF lists approved senders, DKIM adds a digital signature, and DMARC applies rules based on those checks.

2. Data decay. B2B contact lists lose about 22% of addresses per year as people change jobs or domains expire. You can see our blog that goes in depth into data decay here.

3. Low engagement. Consistently low opens or clicks tell providers that your messages have low value, which harms your sender reputation.

4. Shared IP pool.
   Many marketers send from shared IP pools, which is a group of mail servers that share the same sending reputation. If one sender in the pool spams or triggers filters, it can lower inbox placement for everyone using that pool. (Mailgun)

How to Improve Email Deliverability and Inbox Placement

Re-verify every quarter.
Use software validation and human reviews to remove inactive or invalid addresses. See our blog for a detailed guide on how to do this here.

Authenticate fully.
SPF, DKIM, and DMARC alignment is now necessary to meet Gmail and Yahoo standards. To meet these standards, add all three records to your domain’s DNS, and make sure the domain in those records matches the one in your “From” address.

Warm up gradually.
Increase the volume of emails you send for new domains or IPs in stages since large spikes can trigger filters. Start with a small batch of emails, then increase the number slowly to build a stronger sender reputation and to stay out of spam.

Monitor sender reputation and engagement signals.
Remove unopened and bounced emails to maintain domain reputation

Use a dedicated IP if your volume is high enough.
It keeps your sender reputation separate from others.

The Takeaway

In 2025, about 15% of B2B marketing emails never reach the inbox, based on data from GlockApps and other sources. Deliverability remains constant but strict, with one in six emails still lost to filters, bounces, or rejections.

Marketers who treat deliverability as an ongoing effort, and not a one-time task, focus on building trust with inbox providers. They send on a constant schedule, keep lists clean, use proper authentication, and write messages people want to open. Good deliverability comes from constant habits and not a single fix, which is why their emails land in more inboxes.

FAQ

What causes emails to not reach the inbox?

Most delivery failures come from bad lists, expired contacts, missing authentication such as SPF, DKIM, or DMARC, and low engagement that makes senders look unreliable.

How can I improve my inbox placement?

Verify contacts on a regular schedule, authenticate your domain with SPF, DKIM, and DMARC, warm up new domains or IPs in small steps, and remove bounces after every send.

Does Gmail or Yahoo filtering affect B2B senders?

Yes. Google and Yahoo enforce authentication and reputation requirements for all senders as of 2024, so you must comply to maintain deliverability.