10 Non-Intuitive Reasons Why Emails Keep Landing in Spam

10 Non-Intuitive Reasons Why Emails Keep Landing in Spam

Vladyslav Podoliako
Feb 22, 2023
Reading duration
15 min

The world of email marketing is like a minefield — the stakes are high, and the road to success is paved with hurdles. With 85% of all emails being flagged as spam, it's no wonder that businesses worldwide are losing a staggering $20.5 billion annually due to this menace.

But what causes emails to go to spam folders (these dreaded black holes)?
It's not always evident, and even the best practices may not save you from the black hole of emails.

If you're tired of your emails keep going to spam, it's time to look at the non-obvious factors contributing to this email plague. Folderly email deliverability experts who have helped big businesses such as Somnowell Marketing Agency reach a 100% deliverability rate uncover the non-obvious reasons why emails go to spam folders.

So, buckle up and get ready to discover the tricks of the trade to walk through the email marketing minefield like a pro. 😎

FYI: Some insights in this article can make you wonder, “Wow, How could I not have heard that before?”

A Brief Recap:

➡️ Reason #1: You haven't gone through email validation
➡️ Reason #2: You send emails from a misconfigured IP address 
➡️ Reason #3: You're using sloppy HTML
➡️ Reason #4: You forget to authenticate tools used for email outreach
➡️ Reason #5: You send open URLs
➡️ Reason #6: You have no, or a generic, reverse DNS (PTR) record for your IP address
➡️ Reason #7: You send 500+ emails every day (without setting up frequency)
➡️ Reason #8: You don't regularly test your email deliverability
➡️ Reason #9: You haven't set up your email footer
➡️ Reason #10: Your emails are too long
➡️ More Intuitive Reasons to Go Through
➡️ Questions Test Yourself Before Clicking the “Send” Button

Non-Intuitive Reasons Why Your Emails End Up in the (Annoying) Junk Folder

When the question 'why my emails don’t hit inboxes?' appears on your radar, you surely start searching for the most common triggers behind the problem. But often, businesses overlook non-intuitive reasons. The point is that with the development of AI, spam filters are getting only smarter. So get smarter the reasons for getting into a spam folder.

So, here are eight non-obvious reasons hand-picked by Folderly experts (based on 10+ years of experience in fixing email deliverability). Let's get right to the point:

You haven't gone through email validation

Even if you don’t buy email lists and your contacts are carefully handpicked, 22.5% of email addresses become invalid every year. Now imagine how it turns into a 22.5% of bounce rate during the email campaign (whereas the benchmark for bounces is less than 2%). And here, we mean hard bounces that occur when an email is permanently undeliverable due to a recurring issue such as a non-existent email address or a blocked domain.

High hard bounce rates usually pinpoint spammers, and that is why ESPs don’t treat users with high bounce rates well. As a result — poor sender scores and decreased email deliverability rates.

Quick pro-tip from Folderly: verify your contact list once every two months. Different email verification tools available in the market allow you to check a large list of emails for accuracy quickly. As a result, your bounce rate will be low, your reputation as a sender will be high, and your deliverability will be close to 98%.

You send emails from a misconfigured IP address

Usually, you will find your email marked as spam if you don't check the IP configurations before initiating the mailing campaign, both if you are using a new IP or a shared one. Your IP address can be affected by the type of content hosted, frequency of spam, any involvement in malicious activity, length of time in use etc. Unfortunately, it can also easily be used against you by hackers. If the IP has been blacklisted, every email you send will be “blackholed,” bounced back, and/or flagged as spam (even with the best content).

Quick pro-tip from Folderly: regularly check your email IP reputation on your own or with dedicated tools, such as Email Deliverability Audit.

You're using sloppy HTML

One of the biggest myths is that branded HTML emails perform the best. Just think about it — a simpler HTML has a 5.3% higher click-through rate than an HTML-heavy template.

The tricky thing is that spam filters are susceptible to code errors (extra tags, sloppy code, and even the codes pulled from Microsoft Word, or whatever). Besides, most email service providers will block an HTML email if no text copies accompany it. Using HTML becomes even more tricky due to the emergence of new devices that use plain text emails over HTML — smartwatches, gaming devices, voice assistants, etc.

Quick pro-tip from Folderly: always preview what your email layout will look like in the inboxes of all main email providers. Besides, create a text-only counterpart to all your HTML email campaigns to prevent risks. And remember the golden rule — sometimes less is more. For cold emails, we recommend not using images or HTML at all. Finally, if you use images, optimize the size and make it <25KB. 

Check more in our guide on HTML vs. plain text emails.

You forget to authenticate tools used for email outreach

You may team up with a trusted and authenticated Email Service Provider (ESP). However, if you fail to authenticate other email deliverability tools, spam filter gateways will be triggered and will prevent you from sending emails to subscribers.

Quick pro-tip from Folderly: always remember to authenticate not only your ESP but also the cold email outreach tool you use for your email campaigns.

You send open URLs

Always double-check the URLs you send. Present-day scammers are more than eager to use open URLs to direct recipients to malicious resources.

If you happen to use duplicate URLs as scammers do, you will end up on a blacklist in no time. If you don't spot and fix the issue, your emails will keep going to junk.

Quick pro-tip from Folderly: If you include links, make sure they are shorter than 120 characters and are neither broken nor blacklisted. And, instead of using a general purpose link shortener, create your own!

You have no, or a generic, reverse DNS (PTR) record for your IP address

The role of reverse DNS (rDNS) in spam filtering is widely underrated, but as opposed to forward DNS, it is used by email servers to ensure that the sending server is legit. Sending servers with no rDNS intact immediately raises a red flag. In the majority of cases, such servers are scammers, and spam filters are configured to detect them. 

You can relate the rDNS' importance to that of an SPF authentication record. Yet, as opposed to SPF, DKIM, and DMARC records, an rDNS may come as a package deal that some marketing tools offer. Before you let out a sigh of relief, we must inform you that generic rDNS is of little use and usually still compromises your deliverability rates.

Quick pro-tip from Folderly: Make sure you set up a proper rDNS record. Note that it can be done only with dedicated IPs.

You send 500+ emails every day (without setting up frequency)

When you wonder why your sent emails land in the spam folder, try to think about how many emails you send every day. At least 65% of people are in for marketing offers no more than once a month.

 But people’s attention span is limited. So, if you keep showering those 65% with daily emails, sooner or later, they will be flagged as spam, and your reputation and deliverability scores will drop.

Quick pro-tip from Folderly: When you send 500 emails from a newly-registered account, they'll end up in a spam folder. This will happen because that's exactly what spammers do – register email addresses and bombard users with junk. That’s why you need to warmup your domain from the beginning either manually or by asking for Folderly professional help.

Best recommendations from Folderly experts, tested in practice:

- 500 emails a day — general limit
- 200 emails a day — ideal number for your cold outreach emails
- 200 emails a day — for your positive engagement (you can automate it with Folderly Spam Fix or any other tool)
- 100 emails a day — your responses, forwarded messages etc.

You don't regularly test your email deliverability

The simplest reason is often the most underrated. Before you start figuring out how to avoid emails going to spam, you have to be sure of where they land in the first place. And the most common mistake is to think that testing email deliverability occasionally is enough. Good results need persistent work.

Quick pro-tip from Folderly:  Performing testing before starting any email marketing campaign will maximize its effectiveness. Folderly experts have developed an informative and precise email deliverability test that can show your deliverability rate in a few clicks and at no cost. Once you run the test, you will be fully aware of your current deliverability score, what affects it, and how to solve the pressing matter with the least time and effort.

You haven't set up your email footer

Another simple way to fix emails from going to spam is to check the basics. While you pay a lot of attention to the content, header, subject lines, and HTML code of your email, it is essential to prove your trustworthiness as a sender as well. The properly-set footer of the message will help the recipient define your identity, reputation, and legitimacy. 82% of email marketers use email signature marketing to boost brand awareness and improve deliverability.

Expert tip from Folderly: ALWAYS keep your email signature as simple as possible in cold emails. This is the case when less is more. And never ever include images in cold email signatures. 


Your emails are too long

Yeap, even this triggers spam filters. It's true that 500-page books have a lower chance of keeping readers engaged and converting. The same goes for emails.

However, email length can also impact deliverability. Spam filters are designed to identify and block emails that are likely to be spam, and one of the factors they consider is email length. 

Expert tip from Folderly: Less is more. A good rule of thumb is to aim for emails that can be read in less than a minute. The ideal email length is around 50 to 125 words. However, conduct A/B tests to determine the optimal length for your emails. Test different email lengths and monitor the engagement rates for each version. This will help you identify the sweet spot for email length that resonates best with your audience and generates the highest engagement rates.

More Intuitive Reasons To Double Check

As mentioned above – sometimes the answer to the solution to the spam problem lies on the surface. Yet, it's easy to overlook something right before you and start looking for more complex issues and solutions. Just to remind the basics — here are some quite intuitive reasons.

You purchased a contact database (never ever do it)

Most sold contact databases consist of inactive addresses or list those people who aren't even remotely interested in what you are selling. Can you guess the outcome? It might be even more serious than getting into spam filters since harvesting or purchasing email lists for sending commercial messages is against CAN-SPAM Act.

Expert tip from Folderly:  Provide “free cookies” to engage. The healthiest way to collect new emails is by creating a free PDF lead magnet or adding a banner “subscribe to a newsletter.” 


You don't have explicit permission from your recipients

Statistics show 43% of customers will mark promotional emails they receive as spam without double opt-in.Even if you haven't bought any mailing lists, it does not mean you don't need explicit consent from your recipients. The matter goes beyond sharing the same interests with the target audience and acquiring active email addresses. You must give your users a chance to unsubscribe at any time. A double opt-in and proper list segmentation would help you improve your deliverability rate and keep your email from going to spam.

Expert tip from Folderly:  Make the subscription process as easy as possible for users with one click action.


You don't verify emails on your list

Spam signups is a common issue during email campaigns. Malicious Spambots 🤖, disposable email addresses, email aliases (check our expert article on what are email aliases), and other "bad guys" can kill your email deliverability in no time. Email verification or email scrubbing tools will help you to keep your list safe and sound.

You have a high user complaint rate (maybe accidentally)

Even the best marketers get their fair share of user complaints – you can please them all, no matter how hard you try. Ask yourself — when was the last time you checked complaint rates and cleaned the list? Note that the average complaint rate for commercial email is just around 0.12%.

Expert tip from Folderly:  Regularly clean your email list to delete those users who complain. Your domain reputation is much more important than another undesired email that goes nowhere.

Your 'From' information is incorrect/misleading

One of the most common scamming practices is impersonation. Various fraudulent sources play around with their 'from' addresses to resemble legit sources. Thus, spam filters are configured to react to suspicious looking 'from' addresses and ban them from getting into users' primary inboxes. Besides, 68% of Americans say they base their decision to open an email on the “From” line.

You may not have done it on purpose. Sometimes autocorrection or related forms which are supposed to make your life simpler play a cruel trick on you. 

Expert tip from Folderly:  Possible formulas for your “From” line:

✅ ONLY FIRST NAME. It is the best to use when you want to use a conversational tone. For instance, if you are sending first-touch emails with the subject line: “I’m looking for a yoga instructor.” The target business will likely open it, thinking this might be a new lead.

✅ FIRST + LAST NAME. It is best for more formal emails and less-known brands. It is more personal when it comes from a person, and you’re more likely to build interpersonal connections.

✅ FIRST NAME  + COMPANY’S NAME. Such emails usually feel less personal and less intriguing, ideal for recipients involved in B2B start-ups, work as sales or marketing managers, and expect emails from other businesses. 

🚫 COMPANY NAME. Recipients are likely to think it’s just another unsolicited bulk email sent by a machine since they don’t see the person on the other side. It’s okay to use such From Lines for warm emails or product emails, but try to avoid them when it comes to cold email outreach.

Your subject line/email body has spam triggers

Volumes have been published on the importance of subject lines. Just imagine — 69% of email users report emails as spam based only on the subject line.

Yet, not everyone realizes that there is more to spam triggers than just commonly used words. Subject lines that contain all CAPS or are filled with excessive punctuation raise suspicion instantly. Even more, did you know that there are such tricky things as abnormal characters that are not recognized by all ESPs? 

Another tricky thing — some marketers find it witty to start their subject lines with 'RE:' or 'FW:' to attract the reader's attention. However, that is a sure way to go down the deliverability slope since spammers do the same, heavily spicing the line with $ signs and lucrative claims.

Expert tip from Folderly:  check out the recently updated Folderly list of email spam trigger words to make sure none of those ' poisons' your subject lines or message content. If you still need to use spam-triggering words, make sure to use them smartly in the context and limit them to not more than 3 per email. Also, you can use online spam words checker to quickly scan your email copy.

You've included attachments

Oh-oh. No matter how helpful your attachments may be, it's best to keep away from including those. Most scammers use attachments since they are easy to be combined with malicious malware and viruses. Thus, spam filters are stringent when it comes to email attachments.

Expert tip from Folderly:  If you can’t omit to send the attachment in warm email outreach  — upload it to drive and include the link to the file instead of the attachment. However, in cold email outreach, no links should be included.

The reputation of your domain is bad

Spam filters are increasingly relying on domain reputation to evaluate the trustworthiness of email senders. This is because email service providers and different types of emails often use different sending IPs, making it difficult to track the reputation of each IP. However, your domain is likely the same across providers, so it provides a useful way to evaluate your trustworthiness as a sender.

Expert tip from Folderly:  Proactively monitor your domain reputation on a regular basis to ensure that it stays high. Use tools such as Gmail's Postmaster or other services that provide detailed domain reputation scores. Additionally, check if your domain is on any blocklists, as this can have a significant impact on your domain reputation. Services like MXToolBox allow you to check multiple blocklists at once.

Also, remember that each ESP may have unique requirements to follow if you want your email hit inbox. (If you use Mailchimp, we recommend checking the article on why are Mailchimp emails going to spam)

Test Yourself Before Clicking the “Send” Button

Finally, here’s a list of questions to quickly test yourself and make sure you make no one of the discussed mistakes:

  1. Have I thought about who is on my list? Are they blind copied and thoroughly selected? Is every email address still valid?
  2. Have I double-checked and fixed my IP address reputation?
  3. Is my email heave with images? How about HTML? If it is HTML based, have I added text to accompany it?
  4. Have I tested how my email would look in different ESPs? 
  5. Am I sure all the tools I use for email outreach are authenticated?
  6. Did all the people on the list really opt in? (not sort of)
  7. Did I set up reverse DNS? 
  8. Does any part of my email contain all caps? (If so, consider changing it.)
  9. Could this email be shorter? Even more?
  10. Have I attached any files? Am I sure I want (and need) to include them?
  11. Do I have my contact info in the footer or as a signature? (If not, consider adding it).
  12. Do I send no more than 200 cold emails each day? 
  13. Have I warmed up my domain? 
  14. Do I regularly test my email deliverability with professional tools? Or is there a better alternative to Glockapps or Snovio alternative?
  15. Does my “From” line looks credible and aligns with the goal of the email?
  16. Does this email have any animated creatures in the footer? Adorable kittens? How about making it minimalistic to not trigger spam filters and save adorable kittens for another occasion? 
  17. Have I checked my subject line and email copy for spam triggers?

Bonus question: ​​If I had to read this email when having lots of things to do, would I? :) If not, think about whether it is worth user attention.

What Matters Is Integrated Approach

There isn't a single reason that may affect your deliverability scores and lead to the whole, well-planned marketing campaign ending up in the spam folder. Some triggers lie on the surface and are easier to spot, but sometimes they are so evident that we leave them unnoticed. Others are non-intuitive, and you require professional guidance to spot the problem.

375 billion are expected to be sent each day by 2025. Just imagine how it will make email deliverability even stricter. And you should be ready. 

As you see, email deliverability management is a tricky thing. The best way to prevent your emails from going to spam is to explore every potential route with dedicated email deliverability. Contact the Folderly team in case you have any unanswered questions left and a dedicated email deliverability consultant will be happy to help you empower your business with flawless mailbox performance. 

Let’s find a solution and build your personalized email deliverability strategy to make sure your emails are not trapped by spam filters.

+ We also recommend checking our detailed comparison articles, such as Snovio alternative, Glockapps alternative, Warmy Alternative, Warmbox Alternative, Mailwarm Alternative, Lemwarm Alternative, Lemlist Alternative, and Instantly Alternative.

Vladyslav Podoliako
Vladyslav Podoliako
Founder & CEO
Vlad is a Founder & CEO of Belkins and Folderly, a series entrepreneur and investor with over ten years of management expertise in companies with 100 million evaluation. Vlad has years of experience building and growing service companies and SaaS startups in SalesTech and MarTech. He is skilled in creating successful businesses from the ground up and building top-notch teams that drive all ventures to the top of their industries.

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