Gabija from MailerLite

Gabija8 min readTips and resourcesJanuary 31, 2019

How you can improve your own email deliverability (Part 2 of 2)

How you can improve your own email deliverability (Part 2 of 2)

Why do people prune trees? When you remove branches that might cause harm, you enhance the tree’s ability to grow. The health of your subscriber list works the same way!

You spend a lot of time and energy building your email list. The last thing you want is to delete those hard-earned email addresses. But like a tree, the health of your subscriber list depends on pruning the email addresses that are negatively affecting your email deliverability.

What exactly is an unhealthy subscriber email?

Email providers like Gmail, Outlook, and Yahoo monitor how your subscribers interact with your emails. Lower engagement results in poorer deliverability. Unhealthy email addresses are those subscribers who never open your newsletters.

There are two types of unhealthy emails that affect your email deliverability:

  1. Invalid email addresses can originate from simple typos during the sign-up process or from more devious things like bots and spam traps.
  2. Inactive subscribers are people who are no longer interested in your newsletters. They don’t open your emails, which is a problem for your deliverability status.

The good news is once you’ve cleaned up those invalid emails and pruned those inactive subscribers, your deliverability will flourish over time. Ready to make it happen?

Whether you like it or not, your subscriber list contains invalid emails that must be removed before your bounce rate gets too high.

A bounced email is an email that cannot be delivered and is returned to the sender. There are two types of bounces: soft bounces and hard bounces.

email deliverability hard soft bounce example

Bounces, especially hard bounces caused by invalid emails, damage your sender reputation and the deliverability of future newsletters. If your bounce rate creeps above 5%, it means that you have a lot of non-existing email addresses.

To clean your list of invalid emails, you can use a validation tool to verify every address on your list. You can also add some steps to your sign-up process to prevent future invalid emails from infiltrating your list.

Let's go over your options to help you clean your subscriber list and keep it healthy.

Identify and remove invalid emails

It’s really hard to find invalid email addresses by just reviewing your bounces. You want to avoid sending those emails in the first place. The easiest way to identify and remove invalid emails is to use email validation tools.

You can upload your list and the validation technology will detect invalid emails addresses for you to remove. 

You can reduce your bounce rate by 98% and help your newsletters get delivered to the inbox.

Validation tools can also categorize your email list to identify emails that might be spam traps (they can’t identify every one), emails that contain typos and emails with full mailboxes.

Armed with these insights, you can clean and organize your subscriber list to prevent bounces.

Prevent future invalid emails

For starters, the worst thing you can do is purchase a list. You are almost guaranteed to add spam traps and ruin your healthy subscriber list. It’s not worth it!

Beyond not buying lists, the best way to start avoiding invalid email addresses is by adding double opt-in and/or reCAPTCHA features to your sign-up process.

With double opt-in, your new subscribers receive a confirmation email after they sign up. The new address is not placed on your list until a real person confirms the subscription. This serves as a protective shield from email addresses that were submitted with typos, from bot attacks that submit fake email addresses and from adding spam traps.

email deliverability - double opt in example

Please make sure that you are using a proper sender address for your confirmation email and your sending domain is authenticated. Read more about these deliverability best practices here.

You can implement double opt-in in MailerLite on any of the sign-up forms and with API integrations.


The second layer of defense against invalid emails is reCAPTCHA, which is the small checkbox at the end of a sign-up form that usually states, “I am not a robot.”  The primary purpose of reCAPTCHA is to protect websites from spam and abuse by making it hard for bots to sign up on your form. 

email deliverability - recaptcha example

It's super easy to implement and has become a standard practice that people are happy to check when signing up for a newsletter.

If you use MailerLite, you can add reCaptcha by checking the box in your settings. A more detailed description of adding reCaptcha to your sign-up forms can be found here.

Inactive subscribers are people who signed up at one point, but no longer open your emails. They don’t click on any links. They don’t show any signs of life.

Email providers are always checking your opens and clicks to determine if your newsletters are adding value to the recipients. When you keep sending emails to people who are not opening your newsletters, the spam filters will eventually move your newsletter to the spam folder.

If a subscriber has not shown signs of life for six months, you should remove them from your active list. In MailerLite, there is a Clean Up Inactives section in the Subscriber tab, which shows subscribers who have not interacted with any of your emails for the previous six months.

Here’s a quick video tutorial to remove inactive subscribers: 

You don’t have to completely remove those inactive subscribers from your database. You have the option to create a segment of inactive subscribers and set up a re-engagement campaign to win them back.

If they still don’t open your newsletters, you should consider unsubscribing them. It’s hard to say goodbye, but it will ensure that your active subscribers receive your newsletters.

Make it easy to unsubscribe

Did you know that when people unsubscribe from your newsletters, it does not negatively affect your deliverability? For uninterested subscribers, unsubscribing is a good thing.

Many people mark emails as spam just because they can’t find the unsubscribe link. Spam complaints are NOT good for email deliverability. Some email providers will start blocking senders with only 2-3 spam reports per one thousand emails.

Make sure your emails always have a visible unsubscribe link in the footer section.

Think of your unsubscribe link as an automated list-cleaning tool. If people no longer want to hear from you, it’s best to let them go.

Read more on how to customize your Unsubscribe Page.

We want to end this article by listing some common (and avoidable) mistakes related to deliverability.

Mistake #1: Sending newsletters too frequently

Think about your own inbox. It’s a crowded place. Set expectations for your subscribers about the frequency of your newsletters. You can also add preferences to the sign-up form allowing your subscribers to select daily, weekly, or bi-weekly newsletters.

Mistake #2: Grouping active and inactive subscribers

Create segments to differentiate your subscribers based on their activity and other information that you have about them. You can then create more targeted campaigns with better results. Learn more about segmentation here.

Mistake #3: Importing unhealthy email addresses

When you switch email marketing providers, make sure the list of subscribers that you import contains only active subscribers. Never import unsubscribed or bounced subscribers.

Mistake #4: Using old databases of subscribers

Before you send to an old list of subscribers that you haven’t used in a while, verify the list with a validation tool first. If you haven’t contacted a subscriber in over two years, you are not permitted use their email address.

Mistake #5: Using link shorteners

Always add complete links in your newsletters that lead to your website. Link shorteners, such as, are frequently used by fraudulent senders so they can hide the end link destination. Spam filters don’t like link shorteners.

Boost email deliverability with a quality subscriber list

A healthy list means that your subscribers open and read your emails. You avoid bounces and spam traps, improve your engagement metrics and preserve your sender reputation.

As with many things in life, quality outperforms quantity. For trees to flourish, it’s more important to have a few healthy branches rather than a large mix of healthy and unhealthy. The same goes for your subscriber list.

When you prune harmful email addresses, your emails will reach the people you want, enabling your campaigns to thrive.

 Email providers like Gmail, Outlook, and Yahoo will deliver your emails to the inbox when they see that your subscribers are happy to receive and open your newsletters.

For more email deliverability tips, check out PART ONE: How to ensure your emails are deliverable. 

Have you already cleaned your list? What happened to your engagement metrics? 

Please share your experiences below.

Gabija Trimbel

I’m Gabija, Deliverability Manager at MailerLite. I spend my days making sure that your emails are delivered. Email deliverability is a complex and fascinating aspect of email marketing that constantly keeps me on my toes. To be honest, sometimes I wish I had an easier job like a rocket scientist or ninja master.