10 Easy Ways to Boost Your Email Deliverability in 2025

Getting your emails into inboxes is a big deal for any marketing campaign. You can craft the perfect email, but what's the point if it lands in spam? According to Email Tool Tester, the average email deliverability rate in 2024-2025 is around 83.1%, meaning nearly 17% of emails never reach their intended inbox.

So, what’s the deal? Well, every email goes through a journey—first landing at the recipient’s Email Service Provider (ESP), passing through spam filters, and (hopefully) arriving in their inbox. That final step is what we call email deliverability.

Want to improve yours? Here are 10 easy-to-follow steps to keep your emails out of the spam folder in 2025.

1. Protect Your Domain’s Reputation

First, what is domain reputation? Domain reputation is a score assigned to your email-sending domain based on factors like email engagement, spam complaints, and sender behavior. It helps Internet Service Providers (ISPs) and email providers determine whether your emails should be delivered to the inbox, spam folder, or blocked entirely.

Think of it like a credit score for your domain—if your reputation is strong, your emails are more likely to reach inboxes; if it’s poor, they might get flagged as spam.

Your domain reputation is a huge factor in email deliverability, marketing, and communication. To avoid issues, keep an eye on email content, authentication, and your IP address. By protecting it, you ensure your messages consistently reach their intended recipients, helping you build strong relationships and achieve better business results.

2. Avoid Free Email Domains

Using a free email domain might seem convenient, but it can hurt your deliverability, credibility, and overall email marketing performance. For example, using a free email provider like Yahoo, Gmail, or AOL for mass emails is a red flag for spam filters like Spam Assassin. Instead, send from an email that matches your domain (e.g., yourname@yourwebsite.com) to boost credibility, is a simple yet powerful step that improves your chances of reaching inboxes, boosting engagement, and keeping your emails out of spam folders.

3. Use Email Authentication (DKIM, SPF, DMARC)

These might sound technical, but they’re essential:

• DKIM (DomainKeys Identified Mail): You sign the message through cryptographic authentication, protecting your email from being altered on its way by hackers, spammers, etc. Adds a digital signature to prove your email is legit.
• SPF (Sender Policy Framework): This protocol is used by domain owners to prevent spoofing - techniques that aim to mislead users into thinking that a message came from a person or company they either know or trust to steal their data. This is how it works: tells email providers which IPs are allowed to send on your behalf by configuring your SPF as a text record inside the DNS server your domain uses.
• DMARC (Domain-based Message Authentication): Builds on DKIM and SPF and provides reports on failed email attempts, this is an extra security layer you can add to your DNS zone.

If you own a domain, you know that SMTP (Simple Mail Transfer Protocol) facilitates the transmission and delivery of your messages. Setting these steps improves your deliverability and protects your brand from phishing attacks. That’s why many email policies and protocols such as DKIM, SPF, and DMARC are currently used worldwide to prevent fraudulent practices.

4. Don’t Overload Emails with Images

Spam filters don’t like emails that are mostly images. According to Outfunnel, emails with over 50% image content tend to get flagged. Images aren’t bad—they can enhance your emails when used correctly. The key is balance. Aim for a 60-70% text to 30-40% image ratio to keep your emails inbox-friendly. By keeping a healthy text-to-image ratio, optimizing image size, and ensuring your email remains readable even without images, you’ll increase your chances of landing in the inbox rather than the spam folder.

5. Avoid SHOUTING in Your Emails

Using ALL CAPS and excessive !!! In subject lines or body text makes spam filters suspicious. Instead of “ACT NOW!!! LIMITED TIME OFFER!!!” try something more natural like, “Exclusive deal—only available this week.” That is because this practice is often related to spam or fraudulent messages by creating an unnecessary sense of urgency. So, to avoid being trapped and blocked from these filters, do not use only uppercase letters and a lot of exclamation marks in the subject, body, and links of your email campaign.

6. Stay Off the Blacklist

Blacklists are databases of domains or IP addresses known for spammy behavior. Getting on one can damage your email deliverability. Fortunately, there are many ways to prevent being on that list and instead increase your chances of reaching your audience’s inbox. Follow these steps to stay off:

Follow these steps to stay off:

✅ Authenticate your emails

✅ Use an opt-in contact list

✅ Avoid spammy words and formatting

7. Keep Your Email List Clean

Don’t send emails to people who don’t want them! Buying lists or adding random contacts can hurt your sender reputation. Instead, build a permission-based list where people opt-in to receive your emails. Also, you want to keep on your list those who have higher chances of engagement with your emails. You can hurt your deliverability rates by being automatically blocked by the user that simply is not interested in your content. You can avoid that simply by adding an unsubscribe button.

8. Verify Emails in Real Time

Typos happen. When users accidentally enter incorrect email addresses during sign-ups—whether due to misspellings, fake accounts, or disposable email addresses—it leads to hard bounces. A hard bounce occurs when an email is sent to an invalid or nonexistent address, damaging your sender reputation and lowering your deliverability score over time.

To prevent this, you should implement Real-Time Email Verification on your signup forms. This means checking email addresses for accuracy before they are added to your list. Real-time verification tools can detect and flag:

✅ Typos and Formatting Errors – Catch common mistakes like "gnail.com" instead of "gmail.com" or missing "@" symbols before they enter your system. ✅ Fake or Temporary Emails – Some users enter made-up addresses or use temporary email services to access gated content. Verification tools identify and filter these addresses. ✅ Role-Based Addresses – Emails like info@company.com or support@company.com are often shared accounts that don’t engage with emails. These can be flagged to prevent unnecessary sends.

9. Regularly Clean Your List

Did you know email lists decay at a rate of 2% per month? That means 24% of your list could be outdated by year-end. Maintaining a clean email list is essential for improving email deliverability and ensuring your messages reach the right audience. Over time, email lists naturally decay—people change jobs, abandon old email accounts, or lose interest. Use an email checker tool like Emailable to remove inactive addresses and keep engagement rates high. If you send high volumes of emails, consider monthly maintenance to keep your list in optimal condition. By proactively managing your email list, you can maintain strong deliverability rates and ensure long-term email marketing success.

10. Keep track of your Email Deliverability’s health

If you don’t know exactly which issue you are facing, you might need help to diagnose your email deliverability health. Well luckily you can get the help you need with Deliverability by Emailable, a solution that provides reports with insights about your inbox placement and blacklist monitor. We offer you a free 14-day trial to get started.

Final Thoughts: Mastering Email Deliverability in 2025

Email marketing is one of the most effective ways to reach your audience, but it only works if your emails land in their inboxes. With spam filters becoming more sophisticated and email security protocols tightening, ensuring high deliverability is more important than ever.

By following these 10 easy steps, you can significantly improve your chances of reaching your audience, building trust, and driving engagement. Protecting your domain reputation, using proper email authentication, and maintaining a clean, permission-based email list are essential for long-term success. Additionally, small tweaks—like optimizing your text-to-image ratio, avoiding spammy formatting, and staying off blacklists—can make a big difference in ensuring your messages don’t get flagged.

Mailgun’s State of Email Deliverability 2025 report shows that while inbox rates have improved, challenges remain. Following best practices will keep your emails out of spam and in front of your audience.

Now go out there and hit "send" with confidence! 🚀