Cold Email · · 7 min read

Why Are My Emails Going To Spam? What Is Email Deliverability?

Having a good reputation is key to avoiding spam folders, but despite that, outreach emails can still get flagged. Learn how you can pass the spam filters.

why are my emails going to spam

There are a variety of reasons why your emails could be landing in spam folders. Luckily, there are also plenty of steps you can take to avoid triggering spam filters and boosting email deliverability.

Email marketing can yield an ROI of $36 for every dollar spent, making it one of the most effective marketing channels out there. But to get the most out of your outreach campaign, it’s essential to land in the right inbox first.

In this blog, you'll learn all about:

  • How Spam Filters Work
  • Top Reasons Emails Get Flagged as Spam
  • What You Can Do to Improve Deliverability

How To Use Email Warm-Up To Improve Deliverability

To get the best deliverability out of your email it’s essential to do what is called an email warm up. Warming up an email means establishing a good sender reputation to be trusted by email clients and increase your maximum daily sending limit.

To warm up an email you’ll need to consistently send and receive messages between email accounts, which can be a time-consuming process if you plan on doing it manually. Luckily, email warm up can be automated to build a good sender reputation and reach max daily sending limits all on autopilot.

Check out how can boost your deliverability with AI-powered email warm up.

12 Reasons Your Emails Are Going To Spam

A staggering 84.82% of all emails sent are spam, with over 300 billion spam messages sent daily. This unfortunate reality makes it challenging for email marketers to stand out and get past ever-evolving spam filters.

The following list highlights the top reasons that get emails flagged as spam and is an outline of what to avoid when email marketing.

Buying Email Lists

Buying email lists can be done both legally and illegally, but either way, it’s not recommended.

Marketers can purchase lists for their markets through lead gen services, but doing so can cause several issues, such as:

  • It can violate EU online rules of consent laws by contacting people without their given permission. The General Data Protection Regulation (GDPR) privacy law requires an opt-in by individuals before marketing emails can be sent to them.
  • Sending emails to people who haven’t opted-in to receive your messages can be annoying and increase the likelihood of your email getting manually marked as spam.
  • Using a bought email list will increase the chances of sending emails to people outside your target audience or to fake emails that result in a hard bounce.

Using a homegrown email list will avoid all of the above issues and be a lot safer for your sender reputation.

Using Spam Trigger Words or Text

Because of the large amounts of spam sent daily, spam filters have a list of ‘spammy’ words that automatically raise red flags. If there are enough of these in the subject line or within an email, it’s a surefire way to get marked as spam.

Some notable spam triggers are:

  • Free
  • Now
  • Hurry
  • $$$
  • No cost
  • Not spam
  • No startup fee
  • Buy now
  • ! or !!!...

In general, words that convey a sense of urgency, money-related words or anything ‘free’ will likely be on a spam list and should be used as scarcely as possible.

Using Too Many or Lage Images

Images are essential for many types of emails but one of the hallmarks of spam is overly large images meant to grab your attention.

Images are a natural part of newsletters and promotional emails but it helps to stay mindful of the image-to-text ratio, which tip in favor of images for many types of spam. When adding images, be sure to use an image compressor tool to reduce the overall email size.

Your Email Was Manually Marked as Spam

This one is largely out of your control. You can do everything right and still a recipient may mark your email as spam. There can be a host of reasons for this.

The contact may have forgotten they subscribed to you before, or they simply use the ‘Mark as spam’ button to clean out their email. It’s normal to have some people mark your email as spam for whatever reason without affecting deliverability.

The issue arises when a large enough portion of your audience marks your email as spam, which can affect your reputation and cause subsequent emails to automatically land in the spam folder.

Releasing high-quality content and having an opt-in confirmation set up will keep this problem at bay.

Including Attachments

Attachments, especially in a cold email, are an instant red flag for spam filters. They are often used by spammers to send malware or viruses, so not having any attachments is the best course of action.

If you’d like to share a PDF or other file, you can upload it to your site or cloud storage service and include a link in your email. Just be sure not to use…

URL shorteners like are commonly used to track links but at the same time, are also a great way of hiding links to malicious sites or downloads. Like attachments, link shorteners are another major red flag for filters.

Avoid using link shorteners and instead opt for hyperlinked text rather than full URLs (which, like shortened URLs, also trigger spam filters). If you’d like to track link click rates then check with your email provider to see if they offer link click tracking.

Not Including an Unsubscribe Button

Both US and EU internet privacy laws require email subscriptions to have an unsubscribe link clearly in the email. On the outside it’s obvious you don’t want people to unsubscribe, but in reality, giving them the option to do so will help keep your email list clean and full of subscribers that want to receive your messages.

Links to unsubscribe are often placed at the very end of an email in the footer. Not having one not only goes against regulations but is a surefire way to frustrate individuals who want to opt out of future emails to mark your message as spam.

Using an Email That Isn’t Properly Authenticated

Email service providers (ESPs) rely on authentication protocols to know which emails are real and which ones are spam. A common issue for legitimate emails to be treated as spam is not having email authentication properly set up.

You can check your SPF, DKIM, and DMARC statuses to make sure your email authentication is in check. In the case of any issues, your ESP will have a detailed guide on how to set up each one.

Having a High Bounce Rate

An email bounce is when a message fails to deliver and gets bounced back. If it’s a soft bounce then it’s usually due to a temporary technical issue on the recipient’s end.

Unlike a soft bounce, a hard bounce is due to permanent reasons like sending an email to an invalid or fake address. This can happen as a result of buying email lists or not verifying emails before an outreach campaign.

Having a high bounce rate for both soft and hard bounces will significantly impact deliverability and reputation, which can result in emails going to spam or getting rejected by mail servers.

Using Too Much HTML

Too much HTML is a hallmark of spam and can easily trigger filters. A common issue with HTML is it might not render properly by email clients and result in broken HTML icons, which can make an email look sloppy and suspicious.

To create a visually appealing CTA or designs for your email outreach campaign, you can test your HTML code beforehand with online tools like Google’s email markup tester.

Sudden Spike in Email Output

If your campaign starts by sending 100 emails a day and suddenly switches to 10,000 the next, this sudden increase can be interpreted by mail servers as a spam attack.

When looking to increase your daily output, start gradually over a realistic period of time. With you can activate Smart Sending and set daily limits to mimic a natural pattern of sending emails.

Changing Email Service Providers

When switching to a new ESP, an often overlooked step is performing an email warm up for your new email domain to stay out of spam folders. Although it’s possible to keep the same email address with a new provider, the old reputation and level of deliverability will not transfer over, hence requiring a fresh email warm up.

Tips For Improving Email Deliverability

Now that we’ve seen the top things to avoid when sending emails, let’s take a quick look at how you can boost email deliverability in a few simple steps.

Keep Your Email List Up-To-Date

When generating leads it’s easy to rack up a number of fake or unresponsive emails. Keeping your email list clean through bulk email checkers and honoring unsubscribe requests will ensure a low bounce rate.

Tracking open rates and engagement is also key to keeping your list current. Some emails can be collected legitimately but get abandoned over time. A lack of engagement or a soft bounce is one way to spot these types of emails and weed them out.

Test Your Emails Beforehand

Emails look different across different devices and email clients. With 53% of people reading emails on their mobile devices, it’s a good idea to know how your email will look before sending it.

Preview your email by sending out test versions to yourself and other devices. Subject line sizes and snippet features display much differently on Android versus iPhone devices. Knowing or anticipating what devices your target audience uses the most can help fine-tune these details when crafting an email.

Short and Sweet Emails

Sending a pillar sales page as an email will be a red flag for spam filters. Keeping emails concise helps increase readability and engagement, but isn’t always possible.

If you have to write a lengthier email like a publication pitch or a research proposal, then be sure to break it up into multiple paragraphs and spell check thoroughly to satisfy both your reader and spam filters.

Include a Plain Text Option

A plain text version of your email will display it without any HTML, making it more reader-friendly. Offering a plain text version caters to readers on devices or email clients that don’t properly display HTML. In case there are any broken HTML tags (which ideally there shouldn’t be because they trigger spam filters), plain text is an alternative way to show the written content free of HTML.

Add Alt Text to Images

A lot of email clients will prevent images from loading or require a change of settings to load images, especially for cold emails.

If your CTA is in the form of an image, rather than showing up as a white empty box, adding an alt text description will make the alt text visible to readers in place of the blocked image. The text in place of the image will also hyperlink to the intended destination.

Key Takeaways

Taking concrete steps to avoid raising red flags with email clients can make all the difference for your outreach campaign. Even with a meticulously crafted email, not having the technicals down pat can result in a lot of time and effort wasted as your emails land in the wrong folder.

To avoid getting flagged, be sure to:

  • Warm up your email first and foremost.
  • Use tools to check your email’s authentication setup.
  • Steer clear of buying email lists or using spam trigger words.
  • Avoid direct attachments and link shorteners.
  • Make your emails compliant and convenient with an unsubscribe link and plain text option.

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