Why Your Emails Are Landing in Spam Folders

In order to control the flow of spam into inboxes, internet service providers (ISPs) and email clients check each email for spam characteristics. If a message meets their criteria, it gets filtered into the spam folder, available to your recipients but effectively invisible.

According to Statista, 43% of all emails are spam, totalling about 60 billion messages per day, which explains why IPSs and email clients are so aggressive about filtering them out. But many of those emails caught in spam filters are legitimate messages caught erroneously. 

In this article, we explain the top reasons your emails end up in spam folders. We also explain what you can do to keep them out. 

1. Your recipients haven't granted you permission 

A fundamental rule of email marketing is that you should always have permission to send each message to any recipient. Sending emails to recipients that didn't opt in willingly is unethical. In some jurisdictions, it's illegal.

You should never purchase an email list, no matter how relevant the audience seems. Many people will mark your emails as spam if they don’t recognize the sender, even if the content is something they would have subscribed to ordinarily. People care about permission. 

How do people opt into your list? By either completing a form on your website or making a purchase. Keep in mind, however, that submitting their email for a transaction doesn’t give you the right to send marketing messages. You need a special checkbox on your order form that grants you this permission.

2. Your recipient clicked their “spam” button

This is the most common way that your emails end up in spam folders. Sometimes recipients do this because they think the email is unsolicited (even if they request it, perhaps they forgot) or if they don’t want to bother hunting for the “unsubscribe” link.

The only way to prevent this is to create content that’s so compelling and enticing that your recipients want to stay subscribed. This means using captivating subject lines that match the content of the email and filling it with valuable content. 

3. Your subject lines are poor

69% of email recipients report email as spam based on the subject line. This means your subject lines are critically important to the success of your email marketing program.

Misrepresentation is a common reason subscribers hit spam. If they feel misled because of your subject line, they won’t stick around long. In fact, according to the CAN-SPAM Act, it’s actually illegal to intentionally mislead your subscribers.

Your subject lines should be compelling and exciting, but genuine and honest. They should evoke emotion, but relate closely to the content of the email. 

4. Your email engagement is poor

If a majority of your subscribers don’t open your email, it’s a signal to email clients and ISPs that your content isn’t desirable or possibly offensive. This, combined with other spam signals, could get your messages filtered to the spam folder.

How low is too low for engagement? It’s hard to say. The average open rate for retail is about 18%. If you’re under 15%, you should take immediate steps to get more email opens. Read our full guide on boosting your email open rate.

Ultimately, you want to send emails that people want to open. This means it’s super important to create high quality content that matters to your audience. It’s also smart to segment your campaigns so the content is only sent to subscribers who value it the most. 

5. You’re using words that seem spammy

Every ISP and email client has a list of trigger words that get your message sent straight to the spam folder. These are words that have traditionally been used with spammy, low-value content. Sadly, there are a LOT of potential trigger words, depending on the recipient’s email client. Here are a few common words and phrases:

• Amazing
• Cancel at any time
• Please read
• Satisfaction guaranteed
• Dig up dirt on friends
• Check or money order
• Click here
• Congratulations
• Dear friend
• For only ($)
• Free or toll-free
• Great offer
• 100% free
• Best Price
• Discount
• For new customers only
• Offer expires
• Deal ending soon
• Fast cash
• For instant access
• Free consultation
• Guarantee
• Increase sales
• Meet singles
• Limited time
• This is not spam
• Winner

For more comprehensive lists on spam trigger words, check out this guide and this one. 

This doesn’t mean your email will be rejected if it contains any of those words. Having a few trigger words are fine, especially if you’re sending from a reputable IP address and domain, but too many will send your message to spam. 

6. Inaccurate sender information

The “from,” “to,” “reply-to,” and routing information (which means the originating domain and email address) makes up the sender information. If the recipient doesn’t recognize these details, there’s a good chance they will mark the email as spam.
For instance, say you get an email that’s supposedly from Walmart, but the “from” email isn’t a Walmart.com address. Seems suspicious, right? Most people agree and would mark the email as spam, so make sure your send information is honest and accurate.

7. You've included attachments

ISPs and email clients do not like attachments because they are easy places to hide malware. Spam filters often reject messages with attachments outright unless the recipient has a history with the sender. If you need to include a file in the email, either a) get the recipient to whitelist your address, or b) include a link to a cloud storage service like Dropbox or Google Drive.

8. Your IP address has been used for spam

ISPs save lots of data on senders. If your IP address was used for spam in the past, they remember and they share that information with each other. This is another reason it’s important to use an email marketing platform as their IP addresses have good reputations. 

9. There’s no physical address

In many jurisdictions, including the United States, you are required by law to include your physical address somewhere in each email. This gives your recipients an opportunity to contact you if you behave illegally or unethically.

Fortunately, most email marketing platforms require this information before an email can be sent. But if you are using a tool that doesn't have this requirement, make sure to include your physical address in the footer.

10. You’re not using an email marketing platform

An email marketing platform is a service that manages your email list and sends emails on your behalf. These services spend a lot of time and money building their reputations with internet service providers so the emails they send go through. 

By using an email marketing platform, you get to take advantage of their reputation. If you try to send marketing emails from Yahoo, Gmail, or a website that isn’t configured as a mail server, many email clients will flag you as spam. Popular email service providers for ecommerce include Klaviyo, Omnisend, Privy, or Sensorpro.

11. You’ve included too many images

While visual content is important, too many images can trigger spam filters. In the past, some spammers avoided text filters by creating emails that were entirely images. Since the spam filters can’t read images, the spammers could include words that would ordinarily be flagged as spam. We recommend a ratio of 60% text and 40% images. Any higher and you risk triggering those spam filters. 

12. There’s no opt-out link

If you don’t include an easy way for your recipients to remove themselves from your list, their only alternative is to mark your email as spam. In fact, failing to include an unsubscribe link can leave you open to financial penalties in many jurisdictions.

Fortunately, if you use a reputable email marketing platform, the service will force you to add this link before you can send any message to your audience. But if your platform doesn't require this, be sure to add one yourself.

Test If Your Emails Will Hit Spam Filters

Before sending an email, it’s smart to test whether spam filters are likely to flag it as spam. If the email seems “spammy,” you can make changes before sending. The easiest option is Mail Tester. Simply visit the site, copy the email address on the page, and send a test of your newsletter to that address. 

Mail Test will provide a score based on its spamminess (or lack thereof). It will also offer some ways you can fix your mistakes. You don’t have to do this for every single email you create, but it’s a good idea to do this any time you send a unique piece of content. 

Going Forward

As you can see, there are many reasons that your emails might end up in your recipient’s spam folders. Whatever the cause, it’s important to fix those issues quickly so your subscribers get to see your content. Follow the tips we outlined above to get the most value out of your email marketing program.

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