Frustrated that your emails aren’t reaching the inbox? You’re not alone. 

Poor email deliverability means missed opportunities, lower engagement, and wasted marketing efforts and budget. Getting your emails in front of your audience is important for driving conversions and maximizing ROI. 

In this guide, we’ll cover the essential best practices to improve your email deliverability, from optimizing domain reputation to creating content that avoids spam filters. Follow these steps to ensure your emails land where they should—in the inbox, not the spam folder.

What is Email Deliverability?

Email deliverability is about ensuring your emails reach the recipient's inbox, not their spam folder. While delivery rate tracks whether your email was accepted by the recipient’s server, deliverability focuses on inbox placement. Even if your email is delivered, it can still get filtered into spam.

For marketers, deliverability is crucial. It affects whether your audience even sees your message, impacting engagement, conversions, and overall ROI. In cold email outreach, poor deliverability can cripple your efforts, as missed emails mean missed opportunities for leads and sales.

Factors That Affect Email Deliverability

1. Domain Reputation  

Your domain reputation is critical. Internet Service Providers (ISPs) track your domain’s history of sending emails. A poor reputation, often due to high bounce rates or spam complaints, will lead to your emails being flagged as spam. Implementing SPF, DKIM, and DMARC can improve domain trustworthiness.

2. Email Content  

Content is key. Poorly written subject lines, excessive links, or spammy keywords trigger spam filters. Emails with too many images or improper text-to-image ratios can also hurt deliverability. Keep content clean, concise, and relevant to the recipient.

3. Engagement Rates  

ISPs monitor how recipients interact with your emails. Low open rates, high unsubscribe rates, or high bounce rates signal poor engagement. Active engagement—opens, clicks, replies—improves your sender reputation and inbox placement.

4. Spam Triggers  

Certain words, phrases, and formatting raise red flags with spam filters. Avoid all-caps subject lines, too many exclamation marks, and phrases like “Buy now” or “Act fast.” Keep your content natural and informative.

5. IP Reputation  

If you’re using a shared IP address, your deliverability depends on everyone using that IP. A bad actor on the same IP can damage the reputation, leading to deliverability issues for everyone. Consider using a dedicated IP for greater control over your reputation.

6. Authentication Protocols  

Set up SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) to prove that your emails are legitimate and reduce the risk of being flagged as spam. These protocols help ISPs verify that your email is from a trusted source.

Best Practices for Email Deliverability

1. Authenticate Your Emails  

Implement SPF, DKIM, and DMARC to verify your domain’s authenticity and reduce the chances of your emails landing in spam. These protocols tell ISPs that your emails are coming from a trusted sender. Set these up through your email provider (Google Workspace, Office 365, etc.) to safeguard your deliverability.

2. Maintain a Clean Email List  

List hygiene is essential. Regularly clean your email list to remove inactive, invalid, or unengaged contacts. Use double opt-in to ensure recipients truly want your emails, and segment your list to send targeted, relevant messages to engaged users.

3. Use a Reputable ESP (Email Service Provider)  

Choose a trusted ESP like Mailchimp, SendGrid, or Smartlead to manage your email campaigns. Poor-quality ESPs can harm your domain reputation and lead to poor deliverability, especially if they allow users who send spam or fail to manage IP reputation.

4. Avoid Spammy Content

Stay away from spammy words and phrases like “free,” “act now,” or “limited time offer.” Avoid too many images and stick to a simple text-to-image ratio. Consider sending plain text or minimally formatted emails for a more authentic feel.

5. Monitor Your Email Engagement  

Track your open and click rates to gauge engagement. Remove hard bounces and users who mark your emails as spam. Poor engagement rates will flag your emails as low-quality, hurting your sender reputation over time.

6. Use a Warm-up Strategy for New Domains

When using a new domain or IP, start with a low volume of emails and gradually increase it. Abrupt spikes in email volume can alarm ISPs and hurt deliverability. Use Smartlead for automated warmup to slowly build trust for your domain.

7. Keep Emails Relevant and Personalized  

Personalized, relevant content boosts engagement and reduces the chance of being marked as spam. Use dynamic content and segmentation to send messages that resonate with your audience, increasing open and click-through rates.

8. Monitor Blacklists  

Regularly check if your domain or IP has been blacklisted. Tools like GlockApps or MXToolbox can help you monitor your status. If you are blacklisted, follow the process to get removed as soon as possible.

9. Test, Test, Test  

A/B test different subject lines, email formats, and send times to optimize your deliverability. Use tools like Litmus or GlockApps to test how your emails will be treated by spam filters before launching a campaign.

10. Provide an Easy Unsubscribe Option  

Always include a clear and easy-to-find unsubscribe link. Making it hard for users to unsubscribe leads to more spam complaints, which will harm your deliverability in the long run.

5 Tools to Help Improve Email Deliverability

Improving email deliverability requires the right tools to monitor performance, clean lists, and optimize sending practices. Below are some of the top tools that can help ensure your emails land in the inbox.

1. Smartlead and SmartDelivery: The One-Stop Deliverability Solution

When it comes to email deliverability, Smartlead's SmartDelivery is your go-to tool for optimizing email campaigns. Whether you’re a Smartlead user or not, SmartDelivery offers a robust suite of deliverability testing features designed to help you land in the inbox, not the spam folder. 

With SmartDelivery, you can run comprehensive deliverability tests using connected or non-connected email accounts. The tool analyzes key factors such as inbox placement, spam scores, IP reputation, and domain health. 

It also provides detailed reports highlighting potential issues like blacklisting or rDNS failures. You can run manual tests or set up automated tests at scheduled intervals to continuously monitor your campaigns' performance. By simulating real-world sending conditions with features like sending throttling, you can avoid triggering spam filters and improve your overall campaign results.

If you're serious about improving your email outreach, SmartDelivery gives you actionable insights to troubleshoot deliverability problems, all in one platform.

2. GlockApps

GlockApps is another popular tool for deliverability testing. It allows you to check where your emails are landing—inbox, spam, or promotional tabs—across multiple providers. It also monitors your sender IP for any blacklists, ensuring that your reputation stays intact.

3. ZeroBounce

ZeroBounce focuses on cleaning your email list to prevent sending to invalid or outdated addresses, which can harm your sender reputation. Its email verification feature helps reduce bounces, making sure your emails reach valid recipients.

4. Folderly

Folderly specializes in diagnosing and solving deliverability issues. It provides in-depth reports on your sending practices, including spam triggers and sender reputation, helping you adjust your campaigns for optimal performance.

5. MXToolbox

MXToolbox offers valuable tools for troubleshooting DNS records, checking your domain's health, and identifying deliverability issues. It’s essential for anyone looking to ensure proper email authentication with protocols like SPF, DKIM, and DMARC.

FAQs

How do I check if my email is going to spam?  

To check if your email is going to spam, use deliverability testing tools like Smartlead’s SmartDelivery or GlockApps. These tools send test emails to a range of email providers and show where your emails land—inbox, spam, or promotions. They also provide insights into potential issues like spam triggers or domain reputation.

How do I remove my IP/domain from a blacklist?  

First, identify which blacklist your IP or domain is listed on using tools like MXToolbox or Spamhaus. Then, follow the specific removal process for that blacklist. This often involves submitting a request for removal, explaining the cause of the listing, and ensuring the underlying issue—such as spam complaints or bad email practices—is resolved.

Why are my emails landing in the Promotions tab?  

Emails land in the Promotions tab when email providers like Gmail categorize them as promotional content. To avoid this, reduce the use of sales-heavy language, limit the number of links, avoid using too many images, and personalize your emails. Testing with tools like GlockApps can also provide insights into how your emails are categorized.

How many emails should I send daily to maintain good deliverability?  

To maintain good deliverability, it’s best to start slow and gradually increase your sending volume. For cold outreach, aim to send around 50-100 emails per day per email account at first. Warm-up tools like Smartlead’s SmartDelivery can help you ramp up sending volumes safely by increasing email reputation over time.

What’s the difference between delivery and deliverability?  

Delivery refers to whether your email reaches the recipient's server. Deliverability goes a step further, focusing on whether your email makes it to the inbox rather than being marked as spam or landing in the Promotions tab. You can have high delivery rates but poor deliverability if most of your emails are going to spam folders.

Conclusion 

Improving your email deliverability is crucial for maximizing the impact of your campaigns and driving conversions. By following these best practices—optimizing domain reputation, crafting clean email content, and leveraging the right tools—you can ensure your emails consistently land in the inbox.