Klaviyo Emails Going To Spam? Here’s How To Fix It

Written by: Chris Donald

Published on: 31-08-2023

Chris is Managing Partner at InboxArmy and has more than 25 years of experience in email marketing

It can be frustrating to notice a sudden (or even gradual) uptick in the number of Klaviyo emails going to spam, especially if you have a history of healthy deliverability and engagement rates with your audience.

You may be wondering if Klaviyo (or whatever email marketing platform you use) is somehow causing this uptick. But the truth is, Klaviyo is only responsible for sending the emails you construct. If those emails get marked as SPAM, it’s because your subscribers’ email clients are marking them as such due to their own complex algorithms.

Email clients (like Gmail, Yahoo, Outlook, etc.) use complex algorithms to determine which emails to flag and which to allow into a user’s inbox. Since these email clients don’t share information about these algorithms, the only sure way to decrease SPAM rates is to understand the three key deliverability factors that govern whether your emails make it to subscribers’ inboxes and optimize your emails to meet them.

In this article, we’ll break down the three key deliverability factors as well as the specific tactics we use to ensure our clients’ emails avoid SPAM filters. After reading this article, you’ll have everything you need to maximize the deliverability of your Klaviyo emails.

InboxArmy is an email marketing agency that helps clients develop and execute profit-driven email marketing strategies. We’re a Klaviyo email marketing agency with a team of experts on Klaviyo as well as 40+ ESPs. To learn more about how we can help increase your deliverability rates, schedule a free consultation.

The 3 Key Deliverability Factors You Need to Avoid SPAM Filters

The key to avoiding SPAM filters can be summed up in just two words: trust and quality.

Email clients are trying to protect their users from fraudulent emails (i.e., scams) and emails that they don’t enjoy. To avoid SPAM filters and maximize deliverability, you need to send signals that tell email clients that your emails can be trusted and users will enjoy them.

To accomplish this, you need to optimize these three key areas:

  • Domain reputation
  • Email authentication
  • Sender reputation

While email authentication and domain reputation are simpler fixes, optimizing your sender reputation is a more involved process and requires its own section. We’ll start by breaking down each of the three areas, then follow with a section sharing 16 tactics we use to optimize our clients’ sender reputations.

1.) Build a Positive Dedicated Domain Reputation

When sending emails, you can either use a shared or dedicated sending domain.

Shared sending domains are hosted on an IP address that’s shared with other users, such as Klaviyo.com. When using Klaviyo’s shared domain, your sender information will end with the phrase “via Klaviyo.com”.

If you’re using a brand new domain or have no email sending history/reputation, it may be a good idea to use a shared domain at first. Email clients are less likely to trust emails coming from a brand new domain with little/no sending history.

But be careful which shared domain you use. A shared domain’s reputation is impacted by all the people using it. So if other users are engaging in poor or fraudulent email practices, it can hurt your email deliverability rates (though Klaviyo works to ensure users are engaging in positive sending practices, so their shared domain maintains a positive reputation).

It’s best to set up your own dedicated domain so you can:

  • Use your brand’s domain name in your emails
  • Cultivate your own positive sending reputation
  • Avoid any negative impacts from other senders 

Once you’ve set up you’re own dedicated domain, build a positive domain reputation by ensuring your emails are aligned with your domain, using email authentication protocols, and utilizing the tactics we describe in the next section to optimize your sending reputation.

Resources: To learn how to set up a dedicated sending domain in Klaviyo, use their guide.  

2.) Use Email Authentication Protocols and Domain Alignment

In order to protect you and your subscribers from email fraud, email clients use email authentication protocols — such as DKIM (Domain Keys Identified Mail), SPF (Sender Policy Framework), and DMARC (Domain-Based Message Authentication, Reporting, and Conformance).

These authentication protocols ensure that incoming emails are actually coming from a brand’s domain, and aren’t being spoofed or tampered with by malicious 3rd-party actors. 

If your emails aren’t properly authenticated, then email clients are more likely to reject them or send them to SPAM boxes. Email clients also want to see that your sender email address is aligned with your dedicated domain.

To pass this test, you must:

  1. Set up a DMARC policy on your domain.
  2. Connect your dedicated sending domain to your account
  3. Ensure that your root domain of your dedicated sending domain matches the root domain in your sender email address. For example, if your website is business.com (and it has a DMARC policy), your sender address should be something like sender@business.com and your dedicated sending domain should be something like example.business.com.

Use Email Authentication Protocols and Domain Alignment

3.) Sender Reputation

The two factors above are purely about sending trust signals to email clients. But building a positive sender reputation tells email clients that your emails are both trustworthy and enjoyable – which makes optimizing your sender reputation the most important element of avoiding SPAM filters.

Email clients use algorithms that evaluate your reputation as a sender. As stated earlier, they don’t reveal all of the criteria that these algorithms use.

But ultimately, they’re trying to determine how much your current subscribers are enjoying the emails you send so they can ultimately determine how much their users will enjoy your emails.

The path to building a good sender reputation can be summed up simply: send great emails to your subscribers.

More specifically, you want to optimize the following key metrics:

  1. Engagement
  2. Bounce rates
  3. Spam complaints
  4. Unsubscribe rates

In the next section, we’ll break down the specific tactics we use to optimize each.

How to Optimize Your Sender Reputation

By optimizing your email campaigns and strategy according to the four metrics listed above, you will send signals to email clients that their users will open, engage with, and enjoy your emails — which will improve email delivery for Klaviyo or any other ESP (email service provider) you use.

While it’s important to understand these key metrics and how to optimize them, focusing on these metrics isn’t a very effective way to go about improving your sender reputation and deliverability. Especially since some of the tactics we’re about to discuss improve multiple metrics.

The process of improving your sender reputation is easier to understand and apply when broken down into the following objectives:

  • Getting to the inbox
  • Getting your emails opened
  • Increasing email engagement

In this section, we’ll share the 16 tactics and best practices we use to accomplish all three objectives and cultivate positive sender reputations for our clients.

Getting to The Inbox

The first step to increasing email deliverability is to understand the key factors email clients use to spot SPAM so you can remove/reduce them in your emails and sender reputation.

In short, this means:

  • Reducing/avoiding SPAM complaints
  • Reducing/avoiding unsubscribes
  • Reducing bounce rates
  • Eliminating SPAM triggers from your emails

To determine whether to mark your emails as SPAM, email clients evaluate the emails you send and your history as a sender. They look for content in your emails that looks spammy. And they check your history as a sender to see how many SPAM complaints, unsubscribes, and bounces you have.

You can apply the following tactics to eliminate these issues.

Reducing SPAM Complaints, Unsubscribes, & Bounces

Lots of SPAM complaints and unsubscribes indicate to email clients that people aren’t enjoying the emails you send and increase the odds that your emails end up in SPAM folders. Luckily, there are some easy steps you can take to reduce both.

Add unsubscribe links

Ultimately, you want to reduce both SPAM complaints and unsubscribes. But SPAM complaints have a much stronger negative impact on your sender reputation.

So, while it may seem counter-intuitive, you should make it easy for subscribers to unsubscribe from your email list. If someone wants to unsubscribe but can’t easily figure out how, they’re much more likely to mark your emails as SPAM.

Make it easy for people to unsubscribe by adding an unsubscribe link to the bottom of your email. And make sure the unsubscribe link is clear and easy to find.

Add unsubscribe links to klaviyo spam emails

You should also enable “global unsubscribes” in Klaviyo if you have multiple email lists. With “global unsubscribes” enabled, anyone who unsubscribes from one list will be unsubscribed from all.

To enable global unsubscribes in Klaviyo, go to your Email Consent settings and check the box for global unsubscribes.

Unsubscribe behaviour

Enable double opt-in

With a double opt-in, new subscribers will receive an email asking them to confirm that they’d like to subscribe to your email list.

Using a double opt-in has multiple advantages, including:

  • Double opt-ins reduce your bounce rate by automatically filtering out fake email addresses
  • Double opt-ins ensure new subscribers are serious about joining your email list (and are more likely to engage with your emails)
  • Double opt-ins enable you to preempt SPAM designations. In some cases, email clients will automatically send your first email to a new subscriber’s SPAM box. When you set up a double opt-in, you can tell new subscribers to check their SPAM box for your email and mark you as a trusted sender.
  • Double opt-ins prompt immediate engagement. By having new subscribers open your first email and click the confirmation button, you can initiate engagement right away and improve the metrics associated with your sender reputation.

So create a double opt-in automation that tells new subscribers to check their SPAM folder for your first email, mark you as a trusted sender, and click the confirmation link.

To enable double opt-ins in Klaviyo, go to your Consent Settings and click the double opt-in box.

Enable double opt-in in klaviyo email spam

Create responsive emails

Subscribers should be able to view your emails on any device they choose to use. Many people choose to view their emails on mobile devices. If these subscribers can’t see your email because the content won’t load or isn’t optimized for mobile devices, then they’re more likely to unsubscribe — which negatively impacts your deliverability.

Make sure your emails are mobile responsive so subscribers can view them on any device.

Klaviyo allows you to easily optimize your emails for mobile devices. To enable mobile optimization, navigate to your email template’s Style tab and toggle on mobile optimization.

Create responsive emails

Klaviyo also gives you control over how your email is adjusted for mobile devices. You can adjust content margins, text and heading size, text and heading spacing, and block padding.

By default, Klaviyo will stack all content blocks when rendering your email on mobile devices. But you can change this to suit your needs. You can also choose to hide any content block when an email renders on desktop, mobile, or both.

Clean your lists

Clean your email lists by removing:

  • Emails that bounce
  • Unengaged subscribers (people who rarely/never open or engage with your emails)

If your emails regularly bounce for a specific email address, it’s a good indication that the email is fake. While there may be more benign reasons an email bounced (such as the person’s inbox being full), a high bounce rate will harm your sender reputation.

Emails that bounce too often should be purged from your lists. Klaviyo will automatically suppress any email that hard bounces and exclude them from future emails. It does the same for any emails that soft bounce more than 7 times in a row.

But since bounces are harmful to your deliverability, you should create an automation that suppresses soft bounces earlier. We suggest creating a Klaviyo segment that targets anyone who has soft-bounced four times

Similarly, you should remove unengaged subscribers. Unengaged subscribers may eventually mark you as SPAM or unsubscribe from your list. 

Even if they don’t, email clients evaluate your engagement rate among your subscriber list. If a large number of subscribers aren’t engaging, your sender reputation will take a hit. Rather than trying to build a large list of subscribers, your goal as a sender should be to create a large list of engaged subscribers.

For unengaged subscribers, you should create a sunset automation that aims to re-engage them before automatically purging them from your lists.

Create a Sunset Automation

A sunset automation is a series of emails designed to re-engage inactive subscribers before they’re automatically removed from your lists.

Klaviyo enables users to create automated sunset flows for unengaged subscribers based on their behavior over the past 30, 60, 90, 120, and 180 days.  For example, you can create a sunset flow aimed at people who haven’t opened an email in the last 60 days.

The timeframe for triggering a sunset automation will depend on your business and how frequently you send emails. If you send daily emails, then 2-3 months of inactivity is a good timeframe.

Your sunset flow should contain just 1-3 emails — any more risks triggering an unsubscribe and hurting deliverability. These emails should attempt to re-engage subscribers by:

  • Telling them that you noticed they haven’t been engaging with your emails and are attempting to bring them back
  • Asking them why they haven’t engaged with your emails and if there’s anything you can do to bring them back
  • Giving them a special incentive to win their business back, like a discount on their next purchase
  • Letting them know that you will remove them from your list if they don’t respond in a given timeframe, and including a CTA that they can click to stay on your list

To create a sunset flow in Klaviyo, you’ll need to create a segment for each email. For example, your first segment triggers an email to be sent after 60 days of inactivity. Then your second second triggers an email after 90 days, and so forth.

Eliminating SPAM Triggers

There are a few commonalities among SPAM emails that email clients look for when assessing your emails. By removing these, you can significantly increase the odds that your emails end up in the inbox.

Avoid spammy subject lines

It’s tempting to use spammy subject lines to get your subscribers’ attention, but they should be avoided. Not only do they trigger SPAM filters, but 69% of recipients are likely to report an email as SPAM based on the subject line alone.

Use the following tips to avoid creating spammy subject lines:

  • Never use all caps
  • Avoid using excessive exclamation points
  • As often as possible, avoid these SPAM trigger words
  • Make your subject lines consistent with the content of your emails
  • Keep your subject lines at or below 50 characters
Use at least 500 characters

Image-heavy emails may trigger SPAM filters, as spammers often use images to avoid using SPAM trigger words. Make sure your emails contain a proper balance of images and text.

Email on Acid performed a study testing if the text to image ratio of an email affected deliverability. They found that all of the emails they tested that contained 500+ characters successfully avoided SPAM filters.

So make sure your emails contain at least 500 characters.

Don’t add too many URLs

SPAM emails often contain a large number of links. Large amounts of hyperlinked text will trigger SPAM filters.

Don’t include too many links in your emails, and ensure the ones that you do use are well-placed.

Avoid unnecessary code

If you’re manually coding HTML emails, ensure that your code is clean. Unnecessary coding (e.g., extra tags) and coding errors can often trigger SPAM filters.

If you use certain word processors and tools like Microsoft Word to write your code, be careful when copying it over to Klaviyo, as it can often include extra styling. But Klaviyo’s drag-and-drop template editor uses clean code and shouldn’t create this issue.

Getting Your Emails Opened

Now that you made it to a subscriber’s inbox, your next objective is to get your emails opened.

Getting subscribers to regularly open your emails depends largely on your content and the relationship you build with them. If you regularly send emails they enjoy, then they’re more likely to open future emails.

Beyond that, you subject lines and preview text are your second greatest tool for increasing opens. 

Optimize subject lines and preview text

No matter how good your emails are, your subscribers won’t engage if they never open them. Your ability to encourage opens depends almost entirely on how good your subject lines and preview text are.

Invest some time into these areas. For each email, create 5-10 versions of subject lines and preview text. Then pick the best ones.

The same copywriting tactics that work with email copy and landing pages work with subject lines and preview text. We’ve compiled a list of such tactics you can apply immediately. Over time, you’ll get a feel for which work best with your audience.


The simplest path is to simply tell recipients what the email is about. Share a short fact about the contents of your email. The more intriguing the fact, the more opens you’ll get.


Curiosity is a powerful tactic because humans feel compelled to answer open questions. Use your subject lines and preview text to provide some information about your email, but not all.

Think of it like comedy. Your subject line and preview text are the set up. To get the punch line, recipients will have to open the email. The more intriguing the set up, the more people will feel compelled to get the punch line.


Compel your subscribers to take action now by creating a sense of urgency. The easiest way to create urgency is to give them something they want, but only for a limited time.


Exclusivity is another tactic for creating urgency. But rather than using a time limit, you’re applying the concept of scarcity.

Humans like rare things. Rare things are more valuable. And possessing something rare is a sign of status.

If your email contains an exclusive offer, be sure to let subscribers know in the subject line and preview text.


Most emails are boring. Making your emails fun helps them stand out from other emails, boosts engagement, and helps build a strong relationship between you and your audience over time.

Make your subject lines and preview text fun by incorporating playfulness and humor.

Increasing Email Engagement

Engagement is a measure of how often your subscribers interact with your emails (i.e., open your emails and click on email elements), and it may be the most crucial metric of all to optimize.

Engagement is the most direct measure of how much your subscribers enjoy your emails, making it the most direct way for email clients to evaluate the quality of your emails.

While there are many ways to boost engagement, the eight tactics below will have the greatest impact.

Enable subscribers to control their email preferences

If subscribers receive too many emails or emails that they don’t want, they’re less likely to engage with your emails and more likely to mark them as SPAM — which will harm your email deliverability.

One of the best tactics for preventing this is to give subscribers the ability to choose their own email preferences when they sign up.

Your opt-in form should include preference settings, such as:

  • Email Lists: If you have multiple email lists, let subscribers choose which they want to sign up for.
  • Email Frequency: Let subscribers control how often receive emails from you (i.e., daily, weekly, monthly, etc.)
  • Other Email Preferences: If there are any other criteria subscribers can use to personalize their emails, give them the option. For example, if you’re an eCommerce business, you can give subscribers the choice to only receive emails about certain products or categories.

You can create property options in your Klaviyo sign-up forms that allow subscribers to select their preferences.

Be sure to include a link to their subscription management page in your emails so they can adjust their settings when they want.

Segment your lists

In addition to allowing subscribers to segment themselves when they sign-up, you should segment your subscribers into separate lists in order to personalize the content you send them.

Personalizing your content through segmentation can help increase open rates, click rates, conversions, and ROI. It can also potentially decrease email marketing costs by reducing the number of emails you send — i.e., rather than sending every email to every subscriber, you send personalized emails to specific groups.

How you segment your lists will depend upon your business and subscribers. But here are a few strategies you can use:


If there’s any demographic criteria that you can use to segment your audience and increase engagement, you should apply it. For example, if you sell clothing for men and women, you can separate your lists by gender.

Purchase/Website Behavior:

You can combine website analytics with email marketing campaigns to segment lists and personalize emails. Subscribers that buy or click on certain products can be placed in specific lists and receive emails containing content they’re more likely to be interested in.

Engagement Behavior and Frequency:

One of the best ways to avoid SPAM complaints that hurt your deliverability is to segment subscribers by engagement. Separating by engagement enables you to send fewer emails to people who don’t engage with your emails often and send more emails to people that do. 

With Klaviyo, you can create email segments based on:

  • Which email lists they’re on
  • Which actions they’ve performed (i.e., open or click on an email)
  • How many times they performed that action
  • How recently that action was performed (i.e., in the last 30 days)

For example, you can create a segment for Newsletter subscribers who clicked on an email at least 3 times in the last 30 days. These subscribers are more engaged, and likely won’t mind receiving emails more frequently.

But subscribers who haven’t opened or clicked on emails in that last 30 days should probably receive emails less frequently to avoid unsubscribes and SPAM complaints.

Survey your subscribers

Surveys are one of the best email marketing tactics for understanding what your audience wants. Surveys can reveal lots of information you can use to optimize your emails, boost engagement, and grow your sender reputation. And you can use survey results to segment and personalize your email content.

Some areas you can optimize include:

  • Frequency: Ask subscribers how frequently they want to receive emails from you.
  • Timing: Ask subscribers what time of day they prefer to send emails.
  • Content: Ask subscribers what kind of content they enjoy receiving most.
  • Products: Ask subscribers what kind of products they like so you can promote products that align with their interests.

When optimizing your emails, you should always focus on your most engaged subscribers. They’re more likely to respond to surveys. And since you’ll never be able to please everybody, you should focus on the people who engage with your brand the most.

You can use a tool like Typeform to create surveys and send them to your customers. Their responses will be integrated with their profile in Klaviyo as custom properties. You can then create segments that target people with these custom properties with specific emails.

For example, if you’re an eCommerce store that sells shoes, you can create a survey asking subscribers what their favorite type of shoes are. Then create a segment so you can target people with shoes that match their preferences.

Personalize email content

The more relevant your emails are, the more subscribers will engage with them.

We’ve already discussed a few tactics you can use to personalize your emails, such as segmenting subscribers into targeted lists, surveying subscribers to learn what they want, and letting subscribers choose email preferences.

But you can take things a step further by applying the following tactics:

Personalization tags: Personalization tags enable you to create email content that will display different for each recipient. For example, you can use personalization tags to ensure your emails use the recipient’s name in the subject line and at the beginning of an email. Doing so can have a positive impact on open rates and click rates.

Dynamic content: Dynamic content is email content that changes for each subscriber. You can create dynamic content blocks that display products that are unique to each subscriber or segmented list. For example, you can create dynamic content blocks that display products based off a recipient’s purchase history or demographic info.

Create effective CTAs

Compelling CTAs will generate more clicks and help you improve your sender reputation.

Compelling CTAs:

  • Can be easily spotted: Make sure your CTAs are positioned prominently and large enough that recipient’s will see them easily.
  • Stand out: Make your CTAs stand out by creating CTA buttons (rather than hyperlinked text) that pop. Your CTAs should also use colors that contrast from the rest of the email.

Your CTA text should also be optimized for clicks. Use short, direct phrases such as “Buy Now”, “Shop Now”, “Add To Cart”, or “Yes, I Want One”. You can also make them more powerful by including an incentive, such as “Buy For 20% Off”.

Solicit responses

Responding to an email is a strong form of engagement, one that let’s email clients know that subscriber like your brand and the emails you send.

While this tip may not apply to all, you should include content that solicits a response from your subscribers by:

  • Asking for their feedback or opinions on products they purchased
  • Ask the for their input on a new product or initiative
  • Ask them what they enjoy/want more of from your emails
  • Include an incentive for responses, such as a discount or free product

By occasionally creating emails that solicit responses, you can boost your engagement and sender reputation in a very positive way.

Avoid Klaviyo Emails Going To Spam

By applying the tips above, you can enhance your sender reputation, reduce the number of klaviyo emails going to spam folders, and improve the results of your email marketing strategy. 

If you want help improving your Klaviyo email deliverability, Inbox Army provides a team of email marketing experts (including Klaviyo Certified Experts) that can:

  • Identify deliverability issues and determine their cause
  • Create a clear, prioritized list of recommendations to improve deliverability
  • Support your implementation of deliverability improvement recommendations.

To learn more about how Inbox Army can help you improve email deliverability and the other email marketing services we provide, schedule a free consultation.

About Author

Chris sent his first email campaign in 1995. He’s worked directly with Fortune 500 companies, retail giants, nonprofits, SMBs and government agencies in all facets of their email marketing and marketing automation programs. He’s also a BIG baseball fan, loves a good steak, and is mildly obsessed with zombie movies. For more information follow him on linkedin

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