Picture this: It’s the moment you’ve been preparing for. You’ve set up email automation for your marketing campaigns, hooked up your app with a platform to send transactional emails, your marketing team worked diligently on the copy and graphics, you hit send, and the next thing you know… the email is in the spam folder? We gathered information on the 8 main reasons that have an impact on your email's spam destiny and made sure to incorporate prevention tactics so you never have to hear that word again. It's time to put an end to all of the frustration and ensure that your emails end up in the hard earned recipients’ inbox.

Reason #1: You’re not setting up proper email authentication

One of the leading reasons for emails ending up in spam folders (or actually getting stopped by filters prior to that) is that they aren’t compliant with the required authentication processes. Email authentication techniques are used to prevent email fraud, improve email deliverability, and ensure continued delivery by providing information about a sent email’s origin. This process further confirms that the email was indeed sent from the sender listed in the “from” field and wasn’t tampered with while in transit or sent by an imposter.


Take the time to implement proper email authentication methods before sending email. There are four main methods used by ISPs: SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), DMARC (Domain Message Authentication Reporting and Conformance), and BIMI (Brand Indicators for Message Identification).

The DKIM and DMARC methods are especially noteworthy. DKIM provides an encryption key and a digital signature that verifies an email’s authenticity by checking for forging or alterations that would prove otherwise. You can read more about how DKIM works and how to set it up here.

DMARC establishes ways that allow the domain owner to publish their email authentication processes, state which actions to take if an email were to fail authentication, and warrant the reporting of these actions taken on an email falsely claiming to be from the sender’s domain.

Reason #2: Your sender info is inaccurate or misleading

Of the many factors that contribute to a successful email, trustworthiness is of the utmost importance when it comes to determining whether an email will be opened or not. If the recipient doubts your sender info’s (sender name and email address that the received email came from) authenticity and does not trust the sender, they may mark your email as spam, block your address, or unsubscribe from your list, all options which would result in the loss of a contact, opportunity, or a potential customer.

The solution:

Choose an appropriate sender name. Depending on the use case, a good name would be your “Company name” or “First name from Company”. It should also match the email address and the signature found within your email body.

Reason #3: You’re using a dishonest subject line

The nature of your subject line can determine the destiny of your email. It is recommended that you aim to catch the recipient’s attention while avoiding commonly used tactics that cause an email to be blocked or sent to spam. For instance, if your email is inconsistent with what you suggested in your subject line, your prospects are likely to unsubscribe or tag it as spam and complain. In addition, intentionally misleading people with your subject line in order to get them to open your email is not only unethical, but illegal in many countries including the United States,  Canada, most of Europe (and many other countries).

The solution:

Honesty is the best policy. Create a compelling, fun, personalized yet sincere subject line directly related to the content of your email. That way, your customers will feel that they’ve made an informed decision on whether or not to prioritize your email.

Reason #4: You’re using spam triggers

Spam filters are used to wipe out junk from your customers’ inbox, but they can sometimes do their job so devotedly to the point of getting rid of your real emails, too. Many emails that are flagged as spam are flagged as such due to a spammy subject line or spam triggering content. Hence, your choice of words and punctuation are crucial to avoid this happening. Poor grammar, misspelled words, writing in ALL CAPS, and using an excess amount of exclamation marks or emojis, are all common triggers for a spam-alert.

The solution:

Avoid using those spam-triggers mentioned above, don’t begin your subject line with “Re:” or “Fwd:”, don’t use spam words and symbols such as “great offer” or the “$” sign, and always proofread your emails before you hit the send button. Simply make sure that your email doesn’t look like it was written carelessly or generated by a computer.

When sending marketing emails to people without their permission, this behavior becomes counterproductive to all of the hard work you’ve done. You also put your emails at risk for lower open rates, more likely to get flagged as spam, and not to mention the violation of anti-spam and pro-privacy laws such as GDPR, CAN-SPAM, and CASL.

The solution:

Send emails only to those who have provided consent to receive them. In order to do so, you must obtain confirmation from them. A widely used and recommended way to ensure consent is through the use of a double opt-in system: a user signs up for an email marketing list and an email, which includes a link to click and confirm the subscription, is sent out to them. It is only after they’ve hit ‘confirm’ that you’ve obtained explicit confirmation to send them emails. Note that double-opt in is not a legal requirement, but is just a good practice. Don’t forget to make sure that recipients can always unsubscribe or change their email settings regardless of their initial consent.

Reason #6: You’re not monitoring your email list

If your mailing list contains an influx of inactive or disabled accounts, sending emails will result in what’s called a “bounce”. To clarify, inactive accounts are valid email addresses you may have previously emailed to, but now can’t receive your email, most notably because they’ve hit their inbox quota, have been disabled or deleted. Too many bounces will result in lowering your sender reputation, which may eventually land you in the spam-zone.

The solution:

Monitor and update your email list as a routine segment of your workflow:

  • Monitor for bounces and make sure to remove bounced email addresses from your recipient lists.
  • Depending on your use case, find email addresses that have not engaged with your communications over a substantial period of time and remove them from your email list.

Reason #7: Email design

While content conveys important information, design is what really catches the recipient’s eye. Beware, however, certain email designs may possibly catch the unwanted attention of the spam filter.

Poor email layouts and designs that can trigger spam filters include large images (since spammers like to use an entire image instead of text) and HTML that’s not adaptive to the reader’s screen or that intentionally leaves content out of view.

The solution:

There are many design methods that will help you to produce a more engaging email, but here are some important ones that will do just that while avoiding the spam box:

  • Make sure your email isn’t wider than 640px.
  • Keep images as small as possible and your content as concise as possible.
  • Add alt text to your images.
  • Keep a maximum ratio of 60% text to 40% images.

Reason #8: You have low to no sender reputation

Email sender reputation is a score that is assigned to a domain or an IP that sends email. It’s a crucial component impacting your email deliverability.

  • No reputation - when you start out with sending emails, you begin with a clean slate and no reputation, so you're more likely to be flagged as a spammer if your email behavior seems off. Some bad email behaviors include sending 1000 emails per minute, bad email lists, low quality content, and more. Solution: Start off gently and warm up your domain and IP addresses. Don’t forget to add authentication methods to your email domain, and work on avoiding reasons 1-7 mentioned above.
  • Low reputation - if you manage to send enough emails and are left with a low reputation ( due to one of reasons 1-7 mentioned above), you'll have to raise your reputation.

Solution: To achieve this, you have to start by finding the root of the problem and fixing all of the relevant issues. Then, figure out how to get the ratio of complaints+bounces to. sent emails low again.

By following these guidelines, you should now be well on your way to sending properly authenticated, honest, explicitly confirmed, and proofread emails that will surely earn their rightful spots in the correct inbox.

Post photo by Mediocre Studio on Unsplash