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Why emails are going to spam
Priya NainOct 31, 2020 12:00:00 AM20 min read

7 Reasons Why Your Emails Are Going To Spam (With Solutions)

Table of Contents

Email marketing remains a crucial platform for marketers. However, a significant issue they often face is emails landing in the spam folder, causing low open rates.

You might be scratching your head, wondering, "Why are my emails going to spam? I'm not a spammer!" After all, you're not soliciting credit card details or peddling dubious products.

But here's the thing: spam filters don't discern your intentions. They judge you solely based on how you adhere to the rules of email marketing. If you inadvertently mirror the actions of a spammer, you are classified likewise, and your emails end up in the spam folder.

Being marked as spam is more than just a minor inconvenience - it's a serious barrier to your marketing efforts.

Consider this: you have a large email list size with the kind of audience that can be partnered with for tremendous mutual benefit, and you invest tons of energy, brainpower, and money, in strategizing for it. But if your emails end up in spam because of not relying on expert advice or not choosing the right email marketing software that supports all responsible email marketers fairly, then everything is in vain.

Here's the expert advice part we cover for. The software part, we can help you judge for yourself.

Why Spam Is a Problem for Email Marketers

According to Statista, 45% of all emails sent are considered spam, which means your legitimate marketing emails are often battling to be seen amidst a sea of unwanted content. Being flagged as spam leads to lower visibility, decreased trust among your audience, and ultimately, a significant reduction in valuable engagement and conversion opportunities are left unrealized.

Here are 4 reasons why you need to pay attention to your emails landing in the spam folder:

  1. Lower Open Rates: Emails in the spam folder often go unnoticed or are automatically deleted by users. As a result, your open rates suffer, impacting the visibility and engagement of your email campaigns.
  2. Damaged Reputation: Consistently sending emails that end up in spam can harm your sender reputation. Email service providers (ESPs) and internet service providers (ISPs) may flag your domain as untrustworthy, leading to further deliverability issues in the future.
  3. Wasted Resources: Crafting compelling email content, designing visually appealing templates, and segmenting your audience all require time and effort. When your emails go to spam, these resources go to waste, affecting your return on investment (ROI).
  4. Missed Opportunities: Spam-filtered emails can contain important updates, promotions, or valuable content. When recipients don't see these messages, you miss out on opportunities to drive conversions, nurture customer relationships, and achieve your marketing goals.

This is why understanding the issues causing your emails to go to spam is crucial for email marketers like you. By identifying and addressing these problems, you can significantly improve your email deliverability, increase open rates, and ultimately maximize the impact of your email campaigns.

Email gatekeepers keeping spammers away
Email Gatekeepers

So, in this guide, we'll look into the 7 major categories that may be contributing to your emails ending up in the spam folder. Let's bypass those pesky email gatekeepers and boost your email marketing effectiveness.

7 Broad Classes of Reasons Why Emails go to SPAM

  1. Email content is ‘spam-like’
  2. Email design doesn’t follow the protocols
  3. Spam laws are violated
  4. Domain reputation is poor
  5. IP reputation is bad
  6. Email authentication is failing
  7. Email engagement is poor

A lot of factors contribute to the above and here, with this guide, we deconstruct each one of them. If your email is landing in SPAM it is highly likely that you are violating more than 1 law across all categories.

Before that, a quick word on how email delivery infrastructure works.

In order to deal with the email SPAM problem, Internet Service Providers (ISPs) and Email Inbox providers (like Gmail, Yahoo Mail, AOL etc.) rely on SPAM filters, Firewalls and Blacklist directories to keep your inbox free of "Unsolicited” SPAM emails.

I would strongly recommend checking out our definitive guide on email deliverability to learn more about how exactly this works.

To get the most out of this guide, please familiarize yourself with these abbreviations:

ESP - Email Service Provider. By ESP I specifically mean email marketing software (like SendX) that helps you send emails at scale.

Inbox Providers - Companies that provide an Inbox for your emails (Gmail, Yahoo Mail. Outlooks, Hotmail, AOL, Apple Mail etc.)

Spam Filters - Decides whether the email should be present in the inbox, promotions tab, spam folder or whether it should be blocked all together.

IP Address - Internet Protocol Address. In this article's context it refers to the unique public address of the server over which your emails go. This is typically maintained by the ESP.

1. Email content is ‘spam-like’

Keywords in your email body & subject line

Avoid using spam trigger words in your email. These are the words that have been classified as too manipulative, pushy, sleazy or evoking negative emotions.

With sophisticated technologies like AI and Machine Language, email service providers can scan each and every email to determine if it is spam or genuine.

Spelling and Grammar Errors

This is a reason why most scam emails are poorly written - It is not because the scammer has poor English or he is lazy. It is because a poorly written email self selects the most gullible victim.

What would you do if you really get scammed - Report it to the police.

This is a bad outcome for a scammer. They would rather want you to ignore the email Or mark it as SPAM, which is what a poorly worded email does!

Then, it relies on the factor that if you can’t detect their technique of using bad grammar you are probably too gullible or greedy for their offer.

So when you display the same behavior of using poor grammar in your emails, your emails are filtered and sent to the spam folder.

Here are some other factors closely related to the format and readability of your email that are considered while judging whether a mail is spam or not. Avoid all of these:

  • Poorly Written Email Copy
  • Big Fonts and Flashy Color
  • A lot of Exclamations!!!!! and $$$$$$

Links inside the email

If the links inside your emails point to a suspicious domain or a URL which has been flagged as fraudulent then it is very likely your email will land in SPAM.

This can also happen if you are using an email marketing software and the backend they use to rewrite links (to track link clicks) is spammy.

We at SendX have been very careful with this and our tech stack ensures that your links are not looking suspicious. You can try SendX for 14 days for free and check for yourself.

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Using URL shortener in email

A lot of Spammers use URL shortening services like to hide their spammy URL(as they all have access to the same domain and appear the same). Never use generic link shorteners in your emails. However, if you do need to use them, we recommend you use one that allows you to brand the links that you shorten, such as Rebrandly URL Shortener for example


2. Email design doesn’t follow the protocols

Use of Images

Few tips here:

  • Maintain a balance ration or text to image
  • Avoid image only emails
  • Use alt text when embedding images.

Spammers tend to hide all SPAM trigger words in an image and use the email body for neutral words only. Since most SPAM filters do not process the image it gets past them. So, an email with a really skewed ratio of Image/Text can start getting flagged by SPAM filters.

Some users don't allow images in emails to load. The images in your email won’t show to them, making your email look spammy and getting marked as spam. SPAM filters will take this feedback and over a period of time will start considering most of the emails with a similar signature as SPAM.

Example of email with Alt Text

Non-responsive email design

This in itself will not directly cause your emails to land in SPAM.

But, considering that the majority of emails are now opened on a mobile device the likelihood of users marking your email as SPAM will increase if the email does not render properly.

That's why all email templates inside SendX are responsive by default. Not only that, we have created one of the biggest responsive email templates resources on the web (till date). It's available for free.

Example of non-responsive email design

Example of Non-responsive Email Design

Using iframe tag, flash, HTML forms, unsupported HTML tags, CSS attributes, javascript

Email HTML is NOT equal to Web HTML.

There are a lot of obvious HTML tags and CSS attributes that are not supported by major email clients (major culprit being - Microsoft Outlook).

Avoid embedding forms in your email. The submit button of the form will require you to use JavaScript (which is a problem).

Most email clients simply don't support flash content as it is considered unsafe for something as sensitive as email. Email clients block emails containing flash. You can use GIFs and animated flipbooks as an alternative to make your emails more appealing.

Spam filters and more importantly firewalls always take a "better to be safe than sorry" approach. So, all your well-intentioned emails with any type of script will go straight to the SPAM folder.

Missing key elements

If you miss adding key elements like  :

  • from name
  • subject line
  • email body
  • plain text version in your email.

and the email marketing software doesn't have a check or stop you before sending that, then your emails will go into the spam go into the spam folder.

No subject line is used as a marketing tactic to increase opens but it's not worth taking a hit on your IP reputation and deliverability.

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3. Spam laws are violated

Missing Unsubscribe link

All marketing emails need to have a clear way for users to opt-out of them. If you are sending emails to the opted-in list(s) ensure every email going to them has a way to opt out of using an unsubscribe link.

Usually unsubscribe links are present in the footer, but you should include it in the header too. It's not mandated by law (considering you have an unsubscribe link in the email footer) but email providers like Gmail consider this an important signal of reputation. This is how an unsubscribe link in the header looks like:

Unsubscribe link in the Email Header

Unsubscribe Link in the Email Header

Malformed From Email address

Issues with the HTML

If your email has different versions of HTML and plain text email or broken HTML, then your emails will go into the spam folder.

Broken HTML will appear sloppy and unreadable on almost all email clients. Not only will users mark your email as SPAM, but it will also alert SPAM filters (they will think you could be a lazy spammer using unsophisticated tools).

Example of email with broken HTML

Email with broken HTML

An important note here - I have seen way too often, marketers copy content directly from Microsoft Word, Excel, Powerpoint, etc. These applications add additional unwanted characters to your message source. Always copy your content to a plain text editor that strips off all such characters.

All templates we offer for free and every template inside SendX is tested to ensure that HTML is not broken.

Email size > 100KB

Email Acid team did a test on email size and this is what they had to say:

We created text-only, HTML emails in various sizes, from 15-650KB.

We found that sending a file size between 15KB-100KB is A-OK. These emails successfully passed through all our spam filters with flying colors!

Deliverability issues began to occur once the email file size was over 100KB. Every email from 110KB to 650KB wound up failing multiple spam filters. Interestingly enough, once the email file size was over 100KB, the number of spam filters that failed each email stayed the same. For example, an email that was 110KB got caught in the same 7 spam filters as an email with a file size of 650KB.

Multiple studies point out that there is a correlation between email size and deliverability. We would recommend keeping emails between 15KB-100KB to ensure healthy deliverability.

Unsafe OR binary attachment

This is an obvious one. Scammers who use email spam frequently use this technique to steal your data. You would see a warning in Gmail like this:

Unsafe email warning

Unsafe Email Warning

4. Domain reputation is poor

Your domain (which you use to send emails) reputation plays a vital role in your email deliverability. To borrow an analogy from the finance world, it is a lot like a credit score for your email domain. If it is high, you will get good deliverability.

That said, let's deconstruct what are the factors that contribute to it.

Using a free email address as your From Email address

If you are not using an ESP (like SendX) then you will need your own domain to send emails. The reason you can not use a free email address inside a 3rd party system is that they have strict DMARC policies.

If you have your own domain you can set DMARC policies that will tell receiving dedicated servers how to handle emails that have failed the DMARC check.

Using a free email address

Inconsistent Email Volume

This again is the typical behavior of a Spammer. Also, can you think of a legitimate business that will suddenly increase their email volume by 100x?

Sudden changes in email volume are always considered suspicious in the email world.

People marking emails as SPAM

This should not come as a surprise. If people mark your emails as SPAM, your domain reputation will get affected.

When your subscribers click on Mark as SPAM,  a SPAM complaint is logged by mailbox providers like Gmail, Yahoo, AOL, Outlook, etc. notifying ESP's about the same.

Since SPAM complaints are an explicit user signal about unsolicited emails (even a 0.5% SPAM rate is considered really high).

SendX automatically removes all email addresses from your list as soon as we detect they have marked your email as SPAM for the first time. This ensures that you do not send any further emails to those users. We do this to protect the domain reputation of legitimate users.

5. IP reputation is bad

IP is not warmed up properly

IP warm-up is a process to establish a reputation for a new IP. Or an IP that has not been used for some time. This also makes it difficult to send a lot of emails over a new infrastructure. A lot of ESPs do not warm-up their IPs correctly which leads to poor deliverability for their users. If you are facing such issues there is little you can do about it apart from requesting your ESP to move you to a different IP or switch to a new ESP.

IP Server not configured properly

If the backend of the ESP is not configured with proper email header, authentication parameters, and encryption then the emails will get rejected by Email providers (like Gmail, Yahoo Mail, AOL etc.)

Not having TLS Authentication

Email runs over the top of a protocol called SMTP (Simple Mail Transfer Protocol) which is unencrypted by its very nature. TLS or transport level security provides a mechanism to encrypt email messages which prevent the content being read from entities other than the intended recipients.

You can check this using the email headers when you receive them. If your ESP is not using TLS authentication for their IPs, it will affect their reputation.

IP not having Return Path Certificate

Return Path is a company that provides data and insights to help organizations optimize their email marketing. They also provide certificates (to ESPs) that are used as a signal of better authority by major email providers. Check more details.

Not having an inbox for a "from email" OR "reply-to" email address that is used while sending the email over the IP

Now, there could be a scenario when the domain has inbox BUT the "from email" being used while sending the email does not. A common example of this is <no-reply>@ email addresses.

SPAM filters will know this is an invalid email once your receipts try to reply (because the reply emails will bounce). It works either way when you try to send an email on a domain whose email address is invalid, say from your iPhone, it throws an error such as cannot verify server identity due to domain issues or SSL certificate issues (e.g., lack of SSL monitoring).

You will start seeing a hit to your IP reputation if this happens regularly.

6. Email authentication is failing

Email authentication means that you (the owner of the domain) are giving required permissions to a 3rd party ESP, to send emails on your domain's behalf.

It is an important topic if you are using a 3rd party ESP (like SendX). If you are using a mailbox provider like - Gmail, Yahoo Mail, AOL, Apple Mail etc. then your emails will be authenticated by default (if everything is set up correctly).

The top reasons for why email authentication fails would be:

  • Not adding SPF records
  • Not adding DKIM records
  • Not adding (or incorrectly adding) DMARC
  • Using Via Domain
  • Domain being present in email blacklists
  • Domain age.

We cover email authentication and the common mistakes people make when it comes to email authentication, in detail in this SendX blog on why email authentication fails.

At SendX, we provide email authentication for free in every plan and strongly encourage our users (during on-boarding) to get their domain authenticated with SendX.

7. Email Engagement is Poor

The list has inactive members

If a majority of your users don't open your email, email providers have a strong reason to believe that the emails from this domain are no longer adding value.

There is no point in sending emails to a user who does not open your email. You are not only wasting your money but also adding to a poor domain reputation. I can't recommend this enough. Whenever we onboard new customers experiencing low opens, we recommend them to prune their email list, and maintain a valid email list at all times. It would be a good idea to do some in-depth cohort analysis to measure user engagement over a specific period.

From a domain reputation standpoint:

50% email opens for 5,000 subscribers (2,500) > 20% email open for 50,000 subscribers (2,500)

Non-opted-in list

Apart from getting a lot of SPAM complaints and email bounce, people won't engage with your email. So avoid buying lists or scraping emails off the internet.

Not having a double opted-in list

What is better than a Single Opt-In(SOI) list? A double opt-in list (DOI). That said, I must point out that there are valid arguments on either side.

My point of view on this is driven by this simple logic - You don't make money from the size of your list (unless you sell email lists, which I sincerely hope is not the case), you make money when people engage with your emails. DOI leads to better engagement and hence better domain reputation.

Email list size is a vanity metric for most businesses.

Be sure about the value you want to deliver with your email marketing and test out both the SOI and DOI for that. Whichever moves the needle, go for it.

Malformed From Email address

Avoid frequent changes to the From email address field and avoid obscure From email fields like, We strongly recommend our users to use trustworthy email addresses like “feedback@”, “newsletter@”, “support@”, "hello@”, <your_name@> etc.

We can't tell for sure if this goes as a direct signal to SPAM filters but we have seen emails with trustworthy addresses getting much better open rates. Also, weird obscure email addresses can make some users mark them as SPAM (affecting your domain and IP reputation).

Non-segmented campaigns

If you cater to users with multiple interests it is best to segment them based on that and so that you only send relevant emails.

Segments are a combination of (and) and (or) conditions on top of your email lists.

Using segments you can hyper-target your audience.

Segmentation to hyper target audience

SendX has a powerful segment creator to help you do just that. We can help you segment users based on 50+ various attributes like - type of page visited, company name, demographic data such as age, gender, DOB, email opens, clicks. Know more about it by getting in touch with us.

Wrapping up

If a portion of your email traffic is landing in SPAM then you are leaving money on the table.

A portion of your prospects and users are not getting important messages from you like: pricing changes, deal emails, new features, and product updates, upgrade opportunities and a host of other things.

Your revenue is leaking because your emails are landing in SPAM.

But, understanding why your emails are landing in SPAM could be really complicated.

With this guide, we have attempted to lay down all that LAWS that govern the SPAM world.

So, that you are no longer part of the collateral damage in a war being waged against email SPAM.

SendX complies with all the above laws.

In case your emails are landing in SPAM and you are struggling to figure it out all by yourself, reach out to us for help.

Pro tip: In particular, if you are a bulk email sender and have found yourself struggling with the issue of emails ending up in SPAM, then you need to also be aware of Gmail's new requirements for email deliverability.

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1) What exactly is a spam email?

Spam email is any unsolicited email, which is usually sent out in bulk, and which is irrelevant, annoying and sometimes malicious. A few examples are fake lottery win announcements, get rich quick schemes, and fake job schemes.

2) Why do my emails go to spam?

Common reason for emails going to spam are listed as below:

  • Spam trigger keywords in the body
  • Spammy subject lines
  • Absence of unsubscribe link
  • Unsafe attachments
  • Poorly written copy.

3) How can I ensure that my emails don’t go to spam?

In order to ensure that your emails don’t go to spam, you need to adhere to certain rules such as the ones listed below:

  • Send only to opted-in subscribers
  • Explicitly ask subscribers to whitelist your email address
  • Comply with anti-spam laws
  • Proofread your emails to avoid spelling & grammar errors
  • Avoid spam-trigger keywords
  • Send them to a cleaned up list
  • Include an unsubscribe link.

There are quite a few more such rules for this. You can find an extensive list on the SendX blog.

4) How can I know if my emails have gone to spam?

There is actually no way to know whether your email landed in a specific contact’s inbox or SPAM folder once it got delivered. It could have been sent to SPAM by the contact’s email service provider, or the recipient could have manually reported as SPAM, etc.

5) What happens to my sender reputation when my emails go to spam?

If your emails are regularly marked as spam by the recipients, your domain reputation will deteriorate. And based on that, email service providers may automatically send your emails directly to spam.

6) What are the common spammer-behaviors that I can avoid?

Common spammer-behaviors that need to be avoided to ensure that emails don’t land into the spam box are: bad spelling and grammar, image-only emails, and spammy subject lines containing words like “free”, “$$$”, “unlimited” etc.


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Priya Nain

A writer, content marketer, and editor with 4+ years of experience helping SaaS companies get users, and engage them. Nice girl, rarely mean.