Email is a powerful way to reach your target audience and grow your customer base. Nearly 60 percent of users say that marketing emails influence their purchases. However, as online privacy and protection laws tighten, getting your emails into recipients’ inboxes has become tougher.

If your emails are ending up in users’ spam folders, don’t worry. By following some simple best practices, you can not only make sure your emails reach their recipients, but also encourage higher open rates and make a stronger impact.

In this article, we’ll explore why emails end up in spam and what you can do about it.

That’s a lot of ground to cover, so let’s dive in!

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Why Spam Is a Problem for Email Marketers

Estimates indicate that as many as 60 billion spam emails will be sent every day between 2019 and 2023. Obviously, users don’t appreciate that flood of spam. However, this is also a major problem for email marketers. Up to 20 percent of emails will never make it to the recipient’s inbox, preventing you from reaching your audience.

With email delivering an average Return on Investment (ROI) of 122 percent, it’s important to minimize the chance that your messages are in that 20 percent. Every email that lands in spam is wasted money on your part, both for the email itself and any potential conversions it might have generated.

Fortunately, there’s a lot you can do to keep your messages out of spam folders, and most of it is fairly straightforward. In the next section, we’ll look at some of the most common reasons email goes to spam, and see how you can avoid them.

60% of users say that marketing emails influence their purchases... but if your emails are going straight to spam, you're missing out on major marketing impact. 📩 Make sure they reach your audience with this guide ⬇️Click to Tweet

Why Are My Emails Going to Spam? (9 Potential Reasons)

There are numerous reasons emails might be identified as spam, ranging from keywords that trigger spam filters to incorrect permissions.

Let’s walk through some of the most common scenarios, and explore what you can do to make sure your messages land in users’ inboxes.

1. Your Recipients Marked Your Emails as Spam

The first and most obvious reason for your emails ending up in spam is because your recipients put them there.

Even if your content is strong and the recipient expressly gave you permission to contact them, they may still decide to mark your email as spam as a way to clean up a cluttered inbox.

They may also have forgotten why they subscribed to your list in the first place, or simply made a mistake.

Reporting email message as spam
Reporting email message as spam

Unfortunately, if enough of your messages get flagged by users, it can cause spam filters to flag your address and start sending your mail to spam automatically.

This means your messages may end up looking like spam, even to users who haven’t explicitly flagged you in the past. This is especially likely in Gmail, Outlook, Yahoo, and other services with heavily AI-driven algorithms.

Once the email ships, there’s not much you can do to prevent someone from marking your emails as spam.

What you can do is make sure your content is top-notch, and that you follow other best practices to avoid having your email perceived as spam by users. This can minimize the chance that someone will intentionally flag your communications. We’ll cover some of these strategies in the following sections.

2. You’re Not Following HTML Best Practices

While text-only emails are fairly straightforward, they might not be a viable option for some businesses like ecommerce stores as they may lead to lower engagement when compared to emails that include branding, images, and other HTML elements.

However, when including HTML in your messages, it’s important to follow some simple rules to ensure that they don’t end up in spam folders.

Here are some HTML best practices for email, according to Mailchimp:

  • Keep the maximum width of your email between 600 and 800 pixels. This ensures that it’s large enough to read easily, while also behaving well in email client preview panes.
  • Assume that any images will be blocked by email clients and that users may not see critical information if it’s contained within media elements.
  • Keep your code as clean and light as possible, particularly CSS. In addition, avoid JavaScript and Flash entirely. These may be seen as vectors for attack by spam filters, and many email clients don’t support them anyway.
  • Make sure your messages are mobile-friendly. In fact, it’s generally a good idea to design everything with a mobile-first philosophy these days. That means thumb-friendly buttons, small images that won’t overload mobile networks, and email-safe fonts that are readable on small screens.
  • When it comes to fonts, you’ll also want to make sure the ones you choose are cross-platform and clearly legible. Arial, Verdana, and Georgia are all solid options.
  • Review any links added to your email signature, avoiding any websites that might be flagged as spam.

Finally, it’s a good idea to make most of your email’s content text, and minimize the amount of HTML you include. Your company branding and maybe a pop of color can do wonders for engagement, without going overboard.

3. Your Subject Lines Are Misleading or Contain Spam Triggers

Subject lines are typically the first impression a user gets of your message, so they need to grab attention and entice the reader to open the email. However, they also need to be honest. A misleading subject line isn’t just poor etiquette, it’s also against the law, according to the CAN-SPAM Act.

Over half of email respondents report feeling cheated or tricked into opening an email based on the subject line, according to Litmus. That’s a quick way to get your email tossed in the spam folder, and it may even lead some users to unsubscribe.

email headline re
Messages that begin with RE: but are not replies commonly get labeled as spam

What does a misleading subject line look like? Here are some examples:

  • RE or FW. Don’t start your subject lines with “RE” unless you’re actually replying to something. It’s a blatant trick and a quick way to earn an unsubscribe. Similarly, using “FW” can make the person think they know you (the definition of misleading).
  • Personal messages or leading questions. Subjects like “Did I leave my phone at your place?” or “Did you hear about so-and-so?” may make users question whether they know the sender.
  • Overly sensational claims. Some subject lines aren’t necessarily lies but are still a little too over-the-top. In general, you want to make sure that your subject line matches the content the reader will find in the email.

Your subject lines should also be professional. That means no TYPING IN ALL CAPS and definitely no spelling or grammar errors. The free tool Grammarly can check your spelling, grammar, and punctuation automatically, and alert you of any issues that may alert spam filters.

Now you know what subject lines to avoid, but you still need to entice subscribers to open your messages. Hubspot has some excellent recommendations for creating strong headlines:

  • Start with action verbs.
  • Create a sense of urgency and importance (but again, don’t be misleading).
  • Pose an interesting or compelling question.

Finally, remember: whatever your subject line ends up being, make sure the content delivers on its promise. Otherwise, you risk damaging your reputation.

4. You Don’t Have Permission From Your Recipients

This one is simple: online privacy laws like the GDPR require that you must have express permission from recipients in order to send them emails. That means you can’t simply purchase email lists to get quick access to a bunch of contacts (this isn’t a good idea for other reasons, as well, including poor targeting).

However, it also means that even users who provide their email addresses on your site need to explicitly tell you that they want to receive emails from you, especially if they’re a citizen of the EU. This can come in the form of a disclaimer during account creation or on your contact form, or it could be a checkbox that users need to tick to indicate their willingness.

While this isn’t necessarily required in the U.S., it’s still a good practice. People get a lot of emails these days,and if your messages start suddenly appearing in someone’s inbox when they didn’t ask for them, there’s a decent chance they may be marked as spam.

5. Your Content Triggers Spam Filters

Spam filters check for certain words (or combinations of words). If an email gets enough hits or contains those words in addition to some of the other items on this list, it can end up in spam folders. Spam trigger keywords can include:

  • “Free”
  • “Lowest price”
  • “Additional income”
  • “Easy money”
  • “No cost”
  • Multiple exclamation points or dollar signs in a row
  • Words with unnecessary spaces or punctuation
  • Words that are in ALL CAPS

In general, these are words that are either heavily sales-oriented or clearly designed to get around spam filters (such as the extra spaces). While using a handful of these isn’t necessarily a death sentence for your messages, using too many of them can be.

spam headline keywords
Overly ‘salesy’ language and too many keywords can trigger spam filters

Of course, some of these keywords are tough to avoid, especially if you’re sending ecommerce or financial emails. To get around this problem, you can use varied language and try to get creative about how you phrase things.

Above all, it’s smart to avoid pushy or “salesy” language and make sure you’re following proven best practices for writing email content we’re highlighting here.

6. You Don’t Include an Unsubscribe Link

Laws like CAN-SPAM in the U.S. clearly state that your emails must include a clear way to unsubscribe. Additionally, if someone does click on the unsubscribe link, you’ll need to process that request within 10 days, and you can’t force the user to jump through any hoops.

While this might seem like a bad thing (why would you want to give people the chance to unsubscribe?), it can actually have the opposite effect, provided that your content is strong. Giving people an easy way to get off your subscriber list shows that your brand is trustworthy.

On the other hand, hiding or simply not providing an unsubscribe option is a sure-fire way to frustrate people. It can also result in negative press about your newsletter (word travels fast on the internet), and generally rub people the wrong way.

7. Your ‘From’ Information Is Wrong or Misleading

A major reason that your emails may end up in spam is incorrect ‘From’ information. The ‘From’ line, the one that tells your recipients who sent the email, needs to be accurate and not misleading. In some cases, a tool on your site such as a contact form plugin might be sending ‘spoof’ emails with ‘From’ details that trigger spam alerts.

If your contact form emails are getting flagged as spam, the fix is usually pretty simple. You’ll want to make sure that the ‘From’ field in your contact form settings has the admin address for your site, rather than the email address entered into the form. If you’re having the contact form send you email notifications, also make sure the addresses used in ‘From’ and ‘To’ are different.

8. You Haven’t Set Up Email Authentication

Another common reason that your emails’ ‘From’ information may be wrong is when email authentication isn’t properly set up through a service like Mailchimp (or one of its alternatives):

Authentication authorizes the service to send emails on your behalf, so they’ll appear with your domain name attached even though they were sent by a third party. If your authentication isn’t set up properly, your emails can end up going directly to your recipients’ spam boxes.

There are a few different types of email authentication out there, with the main ones being DomainKey Identified Mail (DKIM), Sender Policy Framework (SPF), and DMARC.

DKIM provides an encryption key and digital signature to verify an email, while SPF works by verifying the IP address of the sender against a list of approved IPs. DMARC is a bit different, in that it requires the other two to be enabled and lets the sender indicate that their emails are protected by DKIM or SPF.

If you use an automated email service and you’re having problems with delivery, authentication is a good first thing to check. If you need help with this, we have a handy article detailing exactly how to set up email authentication.

9. You’re Sending Too Many Attachments

Attachments are a huge red flag for most spam filters. This is because files can be easy vectors for malware and viruses. The general rule of thumb is to simply not send any attachments at all, especially in newsletters. If you do need to send an attachment, make sure the recipient is aware ahead of time, and minimize the number of files you attach to a single email.

If you have to attach a document or file to an email, a safer bet is to first upload it to a cloud storage service like Google Drive or Dropbox. You can then include the link to the file in your email. That way, your message shouldn’t trigger any spam filters.

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There are many reasons why your emails might end up in spam folders, from poor subject lines to keywords that trigger spam filters. Whatever the reason, it’s important to resolve the issue to maximize your return on investment and maintain a trustworthy reputation among your audience.

By addressing these problems quickly and implementing some proven best practices, you can easily keep your messages out of spam. Best of all, those same practices can also increase your messages’ impact, and hopefully convert more subscribers into customers.

Do you have any questions about the email marketing best practices outlined above? Let us know in the comments section below!

Matteo Duò

Head of Content at Kinsta and Content Marketing Consultant for WordPress plugin developers. Connect with Matteo on Twitter.