Issue #25

9 steps to improve email deliverability

Email Marketing
26 min read
In this Article

You’ve done the work necessary to attract more email subscribers and entice them to sign up for your email list.

You’ve created email opt-in forms that can be easily placed on your website and blog.

Each lead magnet you’ve published has a corresponding landing page and email sequence connected to it.

All of this means you have a strong foundation for building your email list, but it’s all for naught if you don’t pay attention to maintaining healthy email deliverability.

What determines email deliverability?

First off, deliverability can seem like a very advanced topic. The terms can be very technical and can require a little prerequisite knowledge. If you’d like to catch up or get a refresher on deliverability vocabulary, grab our Deliverability Terms Cheat Sheet below.

Email Deliverability Terms Cheat Sheet

Deliverability refers to the intricate relationship between your IP address, domain reputation, email content, and your subscribers' email provider.

There are several factors that determine how your email is filtered once it’s received by your subscriber’s internet service provider. However, your IP address and domain reputation are likely the most important factors to pay attention to.

What else determines email deliverability? We’ll break down the three biggest factors below.

Subscriber engagement

The more engaged your email subscribers are, the better your email deliverability rates will be. There are several ways to measure subscriber engagement, but all of the metrics are there to help you understand how valuable and relevant your email content is.

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Actions that will positively affect your email deliverability and engagement include:

  • An email subscriber confirming their email address with the double opt-in
  • When someone opens your email broadcast
  • An email subscriber clicking a link in your email
  • When an email subscriber converts and purchases a product or service

Internet service providers want to ensure that the highest quality emails are finding their way into their users inboxes. Because of this, you’ll want to make sure your emails aren’t flagged as spam. This could affect how your emails are delivered in the future.

For example, Gmail will often make assumptions on where to filter your email based on trends they see from your other subscribers. If the majority of subscribers are deleting your emails before they open them, or taking no action at all, Gmail could put you in the spam folder since they don't see positive signals coming from your audience.

What does this mean for you as the sender?

If Gmail sends your emails straight to the spam folder it can lower your overall reputation with Gmail. One way to counteract this is to ask your new subscribers to add your email address to their contact list. This will make your emails always show up in their primary inbox.How to improve email deliverabilty- subscriber engagement

Limiting negative email deliverability metrics

If your email subscriber marks your emails as spam or you receive many hard bounces, it can negatively affect your email deliverability and domain reputation.

Hard bounces often occur when someone buys an email list or double opt-ins aren’t put in place. Many people who buy email lists will find that many of the email addresses no longer exist. But even if the email addresses are still valid, since the subscribers didn’t give you permission to contact them, they will unsubscribe and likely mark you as spam.

Instead, don’t buy email lists and start using double opt-ins. This allows your email subscribers to confirm their email address and their interest in you. When they give you permission to show up in their inbox, they’ll also be more likely to engage with you. This will also keep you from potentially violating the CAN-SPAM Act.

Increasing the quality of your email content

With subscriber engagement in mind, you want to create email content that your subscribers can’t wait to interact with. If your email subscribers are frequently opening your emails and clicking on links, that’s a great sign that they see your email content as higher quality.

You can also use plain-text emails to increase the chances of your email landing in your subscriber’s primary email inbox rather than in the promotions tab.

Plain-text emails feel more like a letter you receive from a friend or coworker, making it a great format to use for your email marketing efforts. If your email features many photos and graphics, it is possible that Gmail and other email providers will automatically categorize your email and put it in the promotions tab.

More ideas to help you increase the quality of your email content:

  • Spend your time crafting thoughtful and engaging email subject lines that are relevant to the content your subscriber will find in the email.
  • Include links to resources with more information.
  • Tell stories your audience will care about.
  • Share insightful tips.
  • Give them an opportunity to join the conversation. How to improve email reputation

How to improve your email deliverability

How do you know if something is affecting your email deliverability? The best way to counteract any negative factors is to follow best practices. You can follow and introduce these recommendations into your email marketing strategy in an hour or less.

Don’t buy email lists

While it may sound tempting to start with an email list that has already been built for you, you should be very wary of email lists you need to buy.

First off, you can’t be sure that everyone on the list gave the email list provider permission to be on the email list, much less to stay on the list if it was sold to someone else.

If you buy an email list, the consequence could be that many of the email subscribers will immediately mark you as spam the minute your first email newsletter hits their inbox. When this happens, it will dramatically decrease your email deliverability rates and could damage your domain reputation.

Just say “no” to buying email lists.

There is no “get rich quick” way to build an email list. Instead, it takes time and energy to grow an engaged audience who can’t wait to hear from you, but you’ll see it pay off when those leads start converting. You don’t need to pay for an email list to start off on the right foot.

Keep a clean list

You only want email subscribers on your list who want to be there. You can quickly tell who those people are by looking at your engagement metrics.

One way to eliminate people who aren’t opening your emails or taking action is by pruning your list of cold subscribers.

Start by locating who the cold subscribers are and tag them inside ConvertKit. Then you can send an email to your cold subscribers that asks them if they are still interested in staying on your list. If they stay silent after a certain time period, you can take them off of your list since they aren’t engaging with your emails anyway.

Create plain-text emails

Skip the complicated designs and save the brilliant visuals you’ve created for other marketing platforms. We recommend creating plain-text emails that focus on your text context. This will result in faster load times and an easy-to-read user experience.

Always ask for permission

To limit spam email addresses and keep a clean email list, use a double opt-in. This will allow new subscribers who are interested in joining your email list to confirm their email address. Only then will they be officially added as a new email subscriber to your list.

You can also give them options to self-select what content they are most interested in during this stage so you only are sending the most relevant information. Some of your email subscribers may be at different stages or interested in different topics, so creating simple email list segments inside ConvertKit will help you stay on top of who receives what email.How to improve email reputation- optimize subject lines

Optimize subject lines

You want your email subject lines to stand out in your email subscriber’s inbox, but you don’t want to turn them off with trigger words or misleading claims. The marketing industry usually considers this “clickbait”, meaning the headline or subject line is disconnected from the actual content inside the email.

This creates confusion for the reader and reduces their trust in the email content you produce. If this happens consistently, they will most likely unsubscribe, but they may also report you as spam. If enough subscribers do this, your email deliverability rates could take a hit.

Keep your subject lines focused on the kind of content you’re creating and use copy that speaks to your ideal customer or client. Also, regularly check your open rates to see how your subject lines are performing. If you see your open rates start to decrease, you can take action by A/B testing different subject line variations until you find the messaging that works.

Create opt-in incentives that attract the right subscribers

Some opt-in offers are better than others when it comes to building an email list full of qualified subscribers. For example, because giveaways and freebies attract a wide range of people, you’ll most likely get a high volume of signups that will never open your later emails or might even move them to their spam folder. Their negative engagement can eventually end up sending your emails to other subscriber’s spam folders as well.

To combat this, make sure your opt-ins are always targeted to an audience that would be interested in your topic. You always want to be attracting readers who would likely open your emails and eventually become customers.

So if you’re planning on running a contest with giveaways, make sure you’re setting yourself up for the outcome. If you’re wanting to grow your list with a targeted audience, create a giveaway that only that group will want. Or if you just want to get your name out there and build a large list, create a giveaway that will appeal to a wide audience.

Add alt text when you use images

Images in and of themselves are not bad. Everyone loves a beautiful picture or graphic and they often help convey a thought or point quicker than actual text. But when you use an image, make sure to write accurate alt text or title instead of simply using the image’s file name. This way if an image gets blocked for any reason, a reader will still know what your image is. This also helps prove that a human sent the email instead of a spam robot.

How to- After you’ve added an image to your email in ConvertKit, click the image again and then click the edit button that pops up. In the edit box, write a title for that image that describes what is happening in your image, ie- your call to action, the details of a promotion.

Watch out for these trigger words

Sadly, because of those spammers out there, there are some words that have developed a bad wrap. When used in subject lines for emails, these trigger words can signal the possibility of spam and usually will send an email straight to the abyss. Here are a couple of those words to avoid in your email subject lines (and your content, if you can):

  • Free
  • Financial freedom
  • Make money online
  • Credit card offer
  • Cash bonus
  • Apply now
  • $$$
  • Weight loss
  • Order now
  • Price
  • Increase sales

Ask subscribers to move emails from their spam or promo folder to their inbox

Sometimes email to new subscribers end up in their spam folder for reasons beyond your control. If those subscribers end up getting in contact with you asking where the email went, ask them to check their spam folder and take a second to move that email from the spam folder to their inbox. It might sound like a silly request, but doing this teaches that ESP that your email actually belongs in the inbox. Doing this will not only help with that particular subscriber's emails, but it will also help similar users whose emails might be ending up in spam as well.

Be consistent with your email delivery schedule

One of the best ways you can manage your complaint rate is by creating a consistent schedule for sending emails to your subscribers. If you typically send one email every two weeks and all of a sudden ramp up to two emails per day during a product launch, you may see an increase in unsubscribes and complaints.

To combat this, stick to a consistent schedule and give your subscribers proper notice if you are going to increase the number of emails you send during a specific length of time.

Always give them the opportunity to not receive launch emails if the product isn’t interesting to them. Not only will you save them from unsubscribing or hurting your email deliverability, but you’ll also preserve the relationship you’ve built with them since they weren’t going to buy anyway.

This will help you avoid what we call “list fatigue”, or the feeling you get as a subscriber when you receive more emails from the sender than you originally anticipated.

Give an easy-to-find unsubscribe link

Let’s change our mindset around unsubscribes. While it may initially seem like a negative thing for someone to unsubscribe from your list, it is actually a blessing.

Why spend time and money nurturing an email subscriber who doesn’t want to read your email content? It’s better for you to cater your email content to people who are loyal subscribers of your brand and interact with your email content consistently.

To keep a clean and healthy list, include an unsubscribe button on the bottom of your emails. This is also required by law due to the CAN-SPAM Act which states that the email sender must allow the recipient to opt-out of receiving emails at any time. It helps to preserve your reputation and gives your email subscriber the power to decide what is relevant to them.

Monitor your email reputation metrics

If you are adhering to the best practices we’ve covered above, your deliverability rates should be healthy and penalty-free. As you put these into practice, also keep an eye on your email reputation metrics to ensure you are giving your email subscribers the best and most relevant content.

The higher the engagement, the better your email deliverability will be.7 email deliverability metrics

7 email deliverability metrics you need to know

While we are on the topic of email marketing metrics, let’s talk about the metrics that will affect your email deliverability. These metrics can take a somewhat confusing concept like email deliverability and break it down into easy-to-measure data points that are simple to track.

If you want to know how well your email marketing efforts are performing, these email deliverability metrics will help. Now let's cover what each metric is and how you can improve your email deliverability rates with them in mind.

Delivery rate

Delivery rate is calculated by the number of people who were tagged to receive your email who actually received it. Your delivery rate can be affected by your email service provider, bounce rates, and other important email deliverability metrics.

It is your email service provider’s primary job to get your emails in the door. That means they are there to help your emails reach as many of your subscribers as possible. Other factors will come into play, but it's important to choose an email service provider with effective delivery rates.

Bounce rate

There are two types of bounce rates you’ll want to pay attention to. A hard bounce means an email address is invalid and should not be sent again. This can happen if the domain they signed up with no longer exists or the email server of the recipient has blocked the delivery of your email.

When a subscriber’s email returns as a hard bounce, your email service provider will mark them as ineligible to receive an email the next time you send an email broadcast to them.

A soft bounce, however, refers to an email that temporarily failed to reach your email subscriber. It could happen because the recipient’s inbox is already full, the email message size is too large to receive, or their email server is down so they can’t receive the email.

If a soft bounce occurs, the email will be resent for up to 72 hours until it is either successfully delivered to the email subscriber or it fails permanently. Unlike hard bounces, soft bounce recipients will still be eligible to receive future emails from you.

Open rate

When you send an email broadcast to your audience, you can see what percentage of people opened your email by looking at your open rate. This is one of the most important email deliverability metrics because it shows the first sign of email subscriber engagement.

To improve your open rates over time, try testing different subject line variations within our A/B testing tool. This allows you to test two variations at a time to see what subject line formats are winning.

Email subject lines are often the first thing an email subscriber sees before opening your email. That means you’ll want to focus your attention here.

Click-through rate

Click-through rates are determined by the number of people who receive your email and click a link inside your email content. This rate is important because it will show you how engaging your email content is.

The more valuable your content is, the more likely your email subscriber will click on the links you provide. You can increase your click-through rate by including additional relevant links for increased click-through opportunities. Continue tweaking your email content and adding value-rich, engaging content that will entice your readers to click.

Click-to-open rate

The click-to-open rate will divide the number of clicks by your percentage of email opens.

This metric is important for measuring the overall success of your email content. This is because it measures how likely someone who actually opened your email is to click on your email. A good click-to-open rate is around 20-30% for promotional campaigns, but you can set your own goals based on how your email content is currently performing.


Your unsubscribe count refers to the number of people who were previously on your list who have now selected to not receive your emails. You may think unsubscribes are all bad, but like we mentioned earlier, they can actually be a good thing!

It’s important to keep an eye on your unsubscribes to see if it spikes with a specific email you send. If so, you might want to assess the relevance of the email.

If the unsubscribes are evenly split between emails and show a minor number, there’s no cause for alarm. Instead, people are just cleaning through their own email inboxes and deciding what content they want to receive.

Spam reports

This refers to the number of people who mark your email as spam. People who mark your email content as spam are immediately taken off of your email list. This is not, however, the same as your email going to the “spam” folder in someone’s inbox. Instead, it is the intentional action someone takes to send a spam report.

The best way to decrease the number of spam reports you receive is to, of course, send very valuable email content and stay consistent. If your email isn't valuable or you send too many emails, you may see a rise in spam reports.

This is a big email deliverability metric you want to avoid, so try keeping an eye on your spam reports and improving your email content over time. You can also add expectations when people sign up for your email list so they know how often and what type of email they will receive.

Tools to use to check your email deliverability

Ready to improve your email deliverability? To find out where you currently stand, there are a few tools you can test.

On the most basic level, MailTester and GlockApps test against Spam Assassin to tell you how your emails are delivering.

Here are a few more advanced deliverability tools:

List Goal

If you want a more comprehensive email marketing dashboard, check out List Goal. It's a web browser extension available for both Chrome and Firefox that offers a free lifetime account to anyone who signs up.

List Goal will:

  • Keep you updated on the overall health of your email list
  • Track your subscriber count
  • Grow your email list to attract more quality leads

It will also alert you if anything goes wonky so you can monitor updates and changes to your list. List Goal also integrates with ConvertKit so you can simply sign up with your email account and connect by providing your ConvertKit API Key.

Return Path

With advanced data and analytic capabilities, email deliverability solution tools like Return Path can help you determine where deliverability rates are going awry and how to fix it.

Sender Score

Sender Score, a Return Path product, will measure the effectiveness of your reputation as an email marketer. Simply add your domain or IP address to their search bar. This will give you access to data to help you improve your email and domain reputation.

Talos Intelligence

Lastly, Talos Intelligence is an in-depth tool that will allow you to keep an eye on your IP address and domain reputation while discovering potential threats to your domain. You can also track your email and spam data over time to see if there are any trends you need to be aware of.

Deliverability terms glossary

Blocklist-This is a list of IP addresses of known spammers, or “spam friendly” servers. If your IP address is on the list, it won't let your email through.

CAN-Spam – Short for ‘Controlling the Assault of Non-Solicited Pornography And Marketing Act of 2003,‘ this law outlines rules for commercial email, establishes requirements for commercial messages, provides email recipients with the right to make you stop emailing them, and lays out consequences for violations of the Act.

CASL regulations- This is Canada’s anti-spam legislation. It’s similar to CAN-SPAM in that it protects consumers against receiving unwanted email but different in that it is much more specific about permission and what is considered “opt-in”.

Domain– Similar to an IP Address, domain names refer to locations of servers and devices connected to the Internet. Domain names can represent many different IP addresses.

Domain Name System (DNS)– DNS is an Internet service that translates domain names into IP addresses.

Domainkeys Identified Mail (DKIM)- DKIM was designed to prevent domain spoofing, or someone pretending to send from your email domain, when they really aren't. DKIM uses cryptographic authentication, which means the records we generate will be unique to you and your domain. Read more about DKIM here.

Double opt-in– With a double opt-in a user is sent an email with a confirmation link after they initially opt-in to your list. After the user clicks the link, they are added to the ongoing email communication. This is a recommended way to build a healthy email marketing list.

Email service provider (ESP)- ESPs provide platforms to send commercial and transactional email on your behalf. ConvertKit is an ESP.

Hard bounce– A hard bounce means that the email address is invalid and should not be sent to again. The email might belong to an unknown user, the content of your email might have triggered their spam filter, or the server might have seen too many other contacts marking your email as spam. When a contact’s email returns a hard bounce, they will be marked as ineligible the next time you include them in a send.

Internet Service Providers (ISP)– ISPs provide mailboxes to end users as part of their paid services. These are generally your cable or Internet providers, such as Comcast and Verizon.

IP Address– A number that uniquely identifies any device connected to the Internet. “IP” stands for “Internet Protocol.” Similar to how a street address helps people find buildings, an IP Address helps computers find each other on the Internet.

Open rate– The percentage of recipients who opened your email message. When someone clicks on an email, an image pixel in the email loads and is counted as an open.

Sender Policy Framework (SPF)- SPF was specifically created to protect against sender address forgery – spammers pretending to send emails as you. An SPF record in your DNS Settings gives email providers something to check, to make sure the emails are really coming from you. Read more about SPF here.

Sender score/reputation– This is basically your rating as an email sender. Return Path’s sender score tool is a free reputation rating tool that rates your outgoing mail server IP on a scale of 0-100. It’s used by mail servers, allowing them to quickly sort email IPs and decide what to do with your email. A sender score that is + 90 is considered a good sender score.

Single opt-in– If an email marketer uses a single opt-in, this usually involves taking a user's form entry and immediately adding that person to a live email list.

Soft Bounce – A soft bounce means that the email temporarily failed to reach its intended recipient. The email will be resent for up to 72 hours or until it’s either successfully delivered or it fails more permanently. Recipients that return soft bounces will still be eligible for future email sends.

Spam complaints (Marked as Spam)- This is the number of contacts that actively marked your email as spam. Contacts that mark your email as spam are automatically unsubscribed from all of your email. Please be aware that Marked as Spam is not the same as an email going into a spam or bulk email folder.

Spam trap/Honeypot– A planted email address designed to catch spammers. For a time, email that hits a dead email address will return a hard bounce. When the mail server sees continued traffic going to the dead address, it can turn the email into a spam trap, accept the email, and report the sender as a spammer.

Allowlist– The opposite of a blocklist, this means your server is considered spam-free or is an “approved sender.” It’s often used by email applications to allow users to mark whether or not they trust emails from specific senders, this overrides some of the filtering that may exist from the ISP. You can also apply for allowlist programs that a few ISPs offer. While not a guarantee to end up in the inbox, a sender may receive preferred delivery as long as they stay within the proper thresholds of the program.


Email deliverability homework assignment

Homework: Improve your email deliverability by creating a cold subscriber re-engagement campaign

You may remember in our email sequences article that we mentioned the importance of keeping a clean email list by regularly pruning your list of cold subscribers. This is so the data you collect represents the most relevant figures based on your current engagement rates.

When you prune your email list, you can set up a cold subscriber re-engagement campaign to see if any cold subscribers want to stay on your list.

You can offer them a re-subscribe link to click that will automatically remove them from your Cold Subscribers tag. Anyone who doesn’t click the link will be deleted as a cold subscriber.

To create this visual automation inside ConvertKit and customize your own cold subscriber email sequence, you can get started with our easy-to-use template!

This visual automation template includes four automation steps and one email sequence that will help you get started. All you have to do is click “Use This Automation” and the content will be copied to your ConvertKit account.

Cold Subscriber Re-engagement Automation

Ready to build your email reputation?

If you’re unhappy with the email deliverability at your current email provider or are looking for an email marketing platform that you can trust, we’d love for you to try ConvertKit.

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Share what you love to connect with your followers and grow your business with a free ConvertKit account.

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Kayla Hollatz

Kayla Hollatz is a copywriter and content creator for creative entrepreneurs who want their words to connect and convert. Few things make her happier than ghostwriting for clients in her studio, aka her four-season porch with a lake view. She can frequently be found fighting Minnesota winters with a mug of hot chocolate in hand.

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