This article breaks down email deliverability and the factors that affect whether your emails reach the inbox or end up in spam. It also shares practical tips to improve deliverability through authentication, list management, and sender reputation.
Email deliverability is the ability of your email messages to successfully land in your recipient's primary inbox. It’s usually tracked by the percentage of emails that internet service providers (ISPs) accept.
While many people associate deliverability with emails that seem to disappear into thin air after sending, there’s more to it. Deliverability also involves inbox placement—meaning whether an email ends up in the main inbox, promotions tab, social tab, or worse, the spam folder.
Why Does Email Deliverability Matter?
Marketers monitor email deliverability to see if messages are actually getting to their subscribers. If emails don’t make it through, campaigns won’t perform, making deliverability a critical metric for every business.
When you send out emails, you expect subscribers to open them and take action. But what happens if your message never even reaches their inbox? That’s not just bad for your audience—it’s also a red flag to your ISP or email service provider.
For example, even with a strong 98% delivery rate, if you’re emailing 1,000 contacts, 20 people still won’t get the email. And of those delivered, only 20–40% might open it. So, where are the rest going? Many likely end up in the spam folder.
The percentage of emails that reach the inbox is referred to as your deliverability rate.
Since it’s hard to track where every email goes, deliverability is mostly inferred. But your goal should always be to give each subscriber a fair chance to see your emails—in other words, you want to hit the inbox every time.
Whether you’re protecting strong deliverability or trying to improve it, here's how to succeed.
What Is a Good Email Deliverability Rate?
A solid delivery rate is anything over 95%. Email platforms like ActiveCampaign will show you the percentage of messages that are delivered, opened, or bounced.
While 100% is the dream, it’s unrealistic, so your goal should be to get as close to it as possible.
There are many factors that affect deliverability. Some are within your control, like list hygiene, and others aren’t, such as technical errors, full inboxes, or temporary server issues.
Let’s explore what affects deliverability and how to fix or prevent issues.
What Is an Email Bounce?
An email bounce happens when a message doesn’t get to the recipient’s inbox, another tab, or even the spam folder. Simply put, the email never reaches them at all.
There are two types of bounces:
1. Soft Bounce
A soft bounce is caused by a temporary delivery issue, such as the recipient’s inbox being full. While more common in the past, they still happen today when there’s a sudden spike in the number of emails you're sending.
ISPs and servers monitor sudden jumps in volume. For instance, if you typically send weekly emails to 1,000 contacts and suddenly jump to daily emails, the sevenfold increase can raise red flags and trigger soft bounces.
2. Hard Bounce
A hard bounce indicates a permanent issue—like the email address doesn’t exist. One or two hard bounces might not hurt, but consistent ones suggest poor list management and can lower your sender reputation.
What Affects Email Deliverability?
Several key elements impact your ability to land in the inbox:
1. Sender Reputation
This is a score that ISPs assign based on your sending behavior. The lower your reputation, the less likely your emails will be delivered successfully.
2. Email Authentication
ISPs verify emails through protocols like SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail). These prove that the sender is legitimate. If there’s a mismatch between the visible sender and the actual server, deliverability takes a hit.
Tools like SPF and DKIM help prevent spoofing. ActiveCampaign even offers a DKIM/SPF checker to help with setup.
3. ISP and Mail Server Infrastructure
Behind every email is a blend of software and hardware. While cloud-based platforms have made things easier, strong infrastructure is still essential. That’s why many businesses use email service providers like ActiveCampaign that can support large email volumes.
4. Low Open Rates Hurt
If your emails are consistently ignored, your sender reputation can drop. This tells inbox providers that people don’t find your messages valuable, making it more likely your emails will be filtered out or flagged as spam.
5. Spam Complaints & Traps
If too many people mark your emails as spam, or if you unknowingly send to spam trap addresses, your domain can be flagged. Spam traps are fake addresses used to catch senders who aren’t properly maintaining their email lists.
Why Email Sender Reputation Matters
All the above factors—open rates, bounces, complaints—contribute to your email sender reputation. A lower score can mean your messages end up in the junk folder or are blocked entirely.
There’s also domain reputation (based on your sending domain) and IP reputation (based on the IP address you’re sending from). These play a huge role in whether your emails are trusted by ISPs.
Email Authentication: SPF & DKIM
SPF
This protocol checks whether your email was sent from an IP that’s authorized to send on behalf of your domain. If the IP isn’t on the list, the email may be rejected.
DKIM
This uses encryption to add a digital signature to your emails. It verifies that the content hasn’t been altered and that the email genuinely came from your domain. DKIM is visible to recipients, helping prevent spoofing and phishing.
Downsides of Improper Authentication
If your SPF and DKIM settings aren’t configured correctly, your emails may fail authentication—even if they’re legitimate. When emails are forwarded or routed through another platform, mismatches in authentication can occur, harming deliverability.
ISP and Mail Service Infrastructure Is Important
Even with great content and clean lists, emails can fail due to technical limitations. This includes outdated servers, incorrect configurations, or high latency. That’s why it’s essential to rely on email platforms with robust infrastructure, like ActiveCampaign, to handle large-scale sends and ensure deliverability.
Low Open Rates Hurt
If you send too many emails that nobody opens, inbox providers may assume your messages aren’t useful. Over time, they could divert your emails to spam or block them entirely.
Low open rates reduce your engagement metrics, which affect your overall sender score. Try segmenting your list or re-engaging inactive users to keep engagement high.
What If Your Email Lands in Spam?
It’s not just annoying—it damages your brand and hurts your chances of reaching the inbox again. The more your emails go to spam, the harder it is to rebuild your reputation.
Check your email content for spammy words, avoid using misleading subject lines, and always ask subscribers to whitelist your address or move you to their primary inbox.
What Happens If You’re Blacklisted?
Email blacklists are databases of known spammers. If you land on one, inbox providers may reject your emails outright. Even if you’re not a spammer, poor practices like sending to outdated lists can get you listed.
There are public and private blacklists, and getting removed often requires proving that you’ve resolved the issue and won’t repeat the behavior.
How to Avoid and Fix Poor Email Deliverability
Here are proactive steps you can take:
- Authenticate your emails using SPF and DKIM.
- Warm up your domain/IP gradually when starting or restarting sending.
- Keep your list clean—remove inactive or bounced addresses.
- Avoid spam triggers in subject lines and body copy.
- Monitor your engagement—track opens, clicks, and complaints.
- Use double opt-in so you know your subscribers want your emails.
- Let people unsubscribe easily to avoid spam complaints.
- Test your emails regularly with tools to check for deliverability issues.