Email Deliverability Tools and Best Practices [Primary Inbox]

Email deliverability is a critical component of any email marketing strategy. If your messages don’t reach your subscribers’ inboxes, your efforts are wasted.

There are four billion daily email users, making email one of the most effective ways to reach an audience. Stats also show that email marketing has an ROI of $36 for every $1 spent. 

To maximize your return on investment and ensure that your emails are reaching your audience, it is essential to understand email deliverability. 

Read on to learn more about email deliverability and how to make sure your messages get where they’re supposed to go.

What Is Email Deliverability?

Email deliverability is a measure of how many emails sent actually reach their intended recipients’ inboxes, as opposed to spam folders or other less visible areas. 

It is determined by the Internet Service Provider (ISP) and email service providers (ESPs) that send the messages through their networks. If an ISP or ESP determines that a message is likely to be spam, it will not be delivered.

So, to ensure your emails reach the right people, it is vital to understand the key factors that can affect deliverability

email deliverability scheme
email deliverability scheme

Key Factors That Impact Email Deliverability

The success or failure of your email campaigns can hinge on the delivery rate of your messages. To maximize deliverability, it is crucial to understand the factors that can influence it. Here are the key elements you should consider:

Your Email Account Sender Reputation

Your email account sender reputation is perhaps the most critical factor in determining your deliverability rate. Your sender reputation reflects your domain and IP address’s trustworthiness, with reputation scores ranging from 0 to 100. ISPs and ESPs use these scores to decide whether or not to deliver your emails. 

The higher your sender reputation, the more likely it is that your messages will reach their intended recipients.

email sender reputation
email sender reputation

Level of Engagement

Another critical factor that can affect your deliverability is the level of engagement with your emails. ISPs and ESPs track how many people open, click, and engage with your emails. 

The more people who open, click and interact with your messages, the higher your sender reputation will be. It is essential to keep an eye on your engagement metrics and adjust your content accordingly to ensure that people are interacting with your emails.

Spam Triggers

Certain “spam triggers” can cause your emails to be filtered into spam folders. Common spam triggers include the use of too many exclamation points, using “spammy” words like “free” or “guarantee” in your subject line, and sending large batches of emails at once. 

Below are 30 most common spam trigger words that you should avoid: 

Avoiding these triggers can help keep your messages out of the spam folder.

6 Effective Ways to Boost Your Email Deliverability

Once you understand the factors that can affect your email deliverability, it is crucial to take the necessary steps to ensure your messages are landing on each recipient’s primary inbox. 

Here are five effective strategies you can use to boost your email deliverability

1. Warm Up Your Email Account

Email warmup is the process of gradually increasing your sending volume over time, which helps improve your sender reputation. 

chart for deciding if you need email warmup
chart for deciding if you need email warmup

Start by sending a few emails daily and gradually increase the volume as your account’s reputation improves. This will help you slowly build up your reputation with ISPs and ESPs, which can increase your deliverability rate. 

The best cold email outreach software have the automatic email warm-up tools built in. 

2. Make Sure SPF, DKIM, and DMARC are Set Up

The next step is to ensure that Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM), as well as the Domain-based Message Authentication, Reporting, and Conformance (DMARC) protocol, are set up on your account. 

How DMARC works
How DMARC works

SPF – prevents spoofing. 
DKIM – confirms the authenticity of your messages.
DMARC – aligns the two protocols. 

These measures help ensure that your emails don’t bounce or end up in a spam folder.

3. Regularly Clean Your Email List

Another critical step is to clean your email list regularly. This involves removing inactive subscribers or invalid email addresses from your list. By taking this step, you can ensure that your messages reach the right people and do not end up in spam folders. This can boost your deliverability rate and improve the overall quality of your email campaigns.

4. Provide an Unsubscribe Option

Providing an unsubscribe option allows people to opt-out of your list if they no longer want to receive your emails. Providing an unsubscribe option is a sign of respect for the recipient and can help keep your list clean, thereby improving your overall deliverability rate. 

5. Include Personalization

Personalization can be a great way to boost your deliverability rate. 

Personalized emails tend to be more engaging than generic messages, and this increased engagement can help improve your sender reputation. You can use personalized subject lines, content, or even the recipient’s name to add an extra touch that will make your emails stand out from the crowd. 

shortcodes in emails
shortcodes in emails

6. Use Double Opt-in Confirmation

One way to reduce your bounce rate is by ensuring that emails on your list are valid. To do this, you can use a double opt-in confirmation process to ensure that people are actively opting in to receive emails from you. 

How it works is that when someone signs up for your list, they’ll receive an email asking them to confirm that they really want to be on the list. This confirmation will help keep your list clean and can significantly improve your deliverability rate

single opt in vs double opt in
single opt in vs double opt in

4 Best Email Deliverability Tools

An email deliverability tool is a great way to ensure that your emails reach the right people without getting caught in spam filters. 

These tools can help you monitor your sender reputation and the health of your email list. Here are some essential tools to consider using:

Read the full Warmy review

Overall rating



7 day trial for free stands at the forefront of cutting-edge warm-up solutions, meticulously crafted to elevate the deliverability of your IP, domain, and email infrastructure. Utilizing advanced AI technology, seamlessly integrates into your mailbox, initiating genuine interactions with recipients to systematically boost your email performance.

Designed to effortlessly synchronize with numerous email service providers, including Gmail, Google Workspace, Outlook, SMTP, Microsoft 365, Zoho, Yahoo, Sendgrid, AWS, and more, this platform boasts standout features. From streamlined setup processes to seamless compatibility with major ESP providers, transparent operations, automated email warming, and real-time engagement with recipients, is dedicated to ensuring optimal email deliverability.

Top Features
  • Enjoy a complimentary 7-day free trial
  • Navigate with ease through the user-friendly interface
  • Experience an automated warming process
  • Monitor progress in real-time
  • Elevate your sender reputation
  • Seamlessly integrate with popular email marketing platforms
  • Access personalized email templates
  • Benefit from 24/7 customer support

Read the full Instantly review

Overall rating



14 day trial for free



Best or unique feature



Email Sequences & Follow-ups


Pricing & Trial


Prospecting & Email Verification


Multichannel Outreach


Personalization & Customizability


Analytics & Metrics


Instantly is an AI-powered email warm up and outreach platform that helps you send more emails while keeping your sender reputation intact. Their email warm-up tool works to gradually increase your sending volume to ensure your messages are reaching your prospects’ inboxes. 

The tool also offers unlimited sending accounts to help you manage and analyze your campaigns and AI Optimization for deliverability & response, which helps to ensure that you receive maximum responses. 

Their goal is to ensure your emails stay out of your recipient’s spam folders, and their growing clientele indicates that they’re doing just that. 

instantly ai screenshot
instantly ai screenshot

Read the full MxToolBox review

Overall rating



Free plan available

MXToolbox is a cloud-based email monitoring solution that helps users monitor and analyze server systems. Millions of large enterprises, mid-size businesses, and small businesses have been using this system to fix a wide range of network infrastructure problems that affect their email hosting services

The tool’s primary features include blacklist monitoring, DNS monitoring, domain health monitoring, HTTP website monitoring, and Mail-flow monitoring. It also helps boost email deliverability with DMARC, DKIM, and SPF. 

Another thing we love about this tool is that it offers bulk lookups, which makes it easier to look for information about multiple domains at once. All in all, MXToolbox is a great tool to consider if you want to enhance your email deliverability.

mxtoolbox screenshot
mxtoolbox screenshot

Read the full NeverBounce review

Overall rating



Usage based pricing

With over 125,000 users, NeverBounce is one of the leading email deliverability solutions on the market. It helps you clean any email list of invalid and incorrect entries and ensure that your message reaches the right people. The tool also allows you to prevent bounces, reduce spam complaints, and improve your overall sender reputation.

The tool also offers real-time email verification, which can check emails in real time as they are entered and determine if they are valid. The tool integrates over 80 products, including MailChimp and HubSpot, and is trusted by some of the biggest companies in the world. 

Neverbounce screenshot
Neverbounce screenshot

Key Takeaways for Email Deliverability

Email deliverability is the ability to reach customers’ primary inboxes with your emails. An email that gets delivered but lands in the spam folder or is not opened is considered an unsuccessful delivery.

Here’s what we covered in the article:

  • The factors that affect email deliverability include sender reputation, level of engagement, and spam triggers.
  • To boost your email deliverability, you need to warm up your email account, which involves increasing the number of emails you send each day over a period of weeks.
  • You should also ensure that SPF, DKIM, and DMARC are set up so your messages are authenticated.
  • You should regularly clean your email list to ensure you send emails to active recipients.
  • Provide an unsubscribe option so people can opt out of your list if they no longer want to receive emails.
  • Personalize your emails with the recipient’s name or other information to increase engagement and improve your sender reputation.
  • Instantly is an AI-powered email warm-up and outreach platform you can use to make sure emails are reaching inboxes.
  • MxToolbox is another great cloud-based email monitoring solution that helps you fix network infrastructure problems affecting email deliverability.
  • NeverBounce is a leading email deliverability solution that helps you clean any email list of invalid and incorrect entries.
Picture of Erkki Muuga

Erkki Muuga

Erkki has over 10 years of experience as a software product manager and a proven track record in building and growing SaaS products. He has a keen eye for key differentiating factors and spotting truly valuable software features that enable business use cases.

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