13 min read

8 Tips To Avoid Emails Going To Spam

Lydia Ume

on Jan 8, 2025

QUICK SUMMARY

Over the years, spam filters have become increasingly sophisticated, making it easier for your emails to land in the spam folder. This guide breaks down why it happens and gives you simple, actionable tips to keep your emails inbox-ready!

TABLE OF CONTENTS Why Emails Go to Spam How To Avoid Spam Filters

If you’re a B2B marketer, few things frustrate more than than your emails going to spam instead of your recipients’ inboxes. It’s not just annoying—it’s costly. Missed emails mean missed opportunities, lower ROI, and potential harm to your brand’s reputation.

In this article, we’ll explore why your emails end up in spam, explain how email filters actually work, and dissect the key factors that influence those filters. Most importantly, you’ll get actionable tips to avoid emails going to spam—like how to write emails that stay out of the spam folder and make it to your audience’s inbox where they belong.

Let’s get those email marketing campaigns seen (and opened).

Why Do Emails Go To Spam?

In December 2024, spam messages accounted for more than 46.8% of email traffic. The most common type being marketing/advertising emails. These account for nearly 36% of all spam emails.

Why do these emails go to spam? There are numerous reasons.

One of the top ones is low engagement rates. Email service providers (ESP) like Yahoo and Gmail closely monitor how recipients interact with your email campaigns.

If your open rates are dismal or people rarely click on your links, it signals to these platforms that your content may not be valuable or desired. Over time, this lack of engagement can trigger email filtering algorithms to flag your emails as spam, regardless of how great your offer or email content might be.

Another reason is the sender's reputation. Internet Service Providers (ISPs) assign a trust score that reflects your domain’s email practices. If you’re frequently sending to invalid addresses, your emails bounce too often, or recipients mark them as spam, your domain reputation will plummet.

A low sender reputation makes it nearly impossible to avoid spam filters, even if your content is squeaky clean.

Also, your emails can go to the spam folder based on how they are written and formatted. Emails packed with certain trigger words like ‘free,’ ‘guaranteed,’ or ‘act now’ can raise red flags. Similarly, a poor balance between text and images, broken links, or overly complex formatting can confuse email filtering systems, causing your message to be filtered out.

Finally, failing to follow email best practices can also get your messages flagged. Not including a clear unsubscribe link or sending emails to people who didn’t opt-in to your email list are major red flags for both recipients and email providers. These practices can lead to higher spam complaint rates, damaging your credibility further.

How Email Filters Work

Spam filters are tools designed to analyze incoming emails to identify those that may be harmful or unwanted. They’re like a digital security guard for your inbox. But how does the detection process work?

At the heart of it is the use of heuristics. Email filters assess emails based on predefined rules. These rules assign a score to an email. If the score exceeds a certain point, the email is flagged and filtered out. Spam filters typically analyze three key components of an email:

The content is first scanned for red flags such as spammy keywords, suspicious links, or excessive images.
Then the sender’s legitimacy is evaluated, often by checking authentication protocols like SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) or referencing blocklists that flag IP addresses associated with spam.
Finally, filters assess user engagement patterns, such as whether similar emails are frequently ignored or marked as spam by other recipients.

Most of this filtering happens automatically on servers, such as the SMTP (Simple Mail Transfer Protocol) servers, which process inbound and outbound email traffic. The email service providers also integrates spam filters that categorize emails into folders like ‘Spam,’ ‘Promotions,’ or ‘Social,’ while also allowing users to create custom rules for added control.

How To Write Emails That Avoid Spam Filters

Your email recipients can only interact with what’s in their inbox. So avoiding spam filters is a must. Let’s walk through how to do this so you can improve your email deliverability:

1. Authenticate Your Emails

Email authentication is how you signal to email clients like Outlook and Gmail that yours are legitimate emails. When your emails are authenticated, this prevents scammers from mimicking your address via phishing. This gives your messages a much better chance of reaching your recipient’s inbox. To authenticate your emails, ensure:

Your from address and from name are always consistent. This can help you build brand recognition and trust, making your recipients less susceptible to phishing attacks.
Create a Sender Policy Framework (SPF) record on your domain’s DNS settings. This specifies servers authorized to send emails from your domain name. When you send emails, the server checks to be sure it’s coming from one of the authorized servers in your SPF record.
Create DomainKeys Identified Mail (DKIM) signatures for your emails. This works like signing a letter with your signature or stamp so that the recipient knows that the message is indeed from you and not spammers. However, DKIM uses a private key, a secret code if you will, which must match with a public one. The receiving server compares these two keys to ascertain authenticity.
If SPF and DKIM fail, ESPs fall back on Domain-based Message Authentication, Reporting and Conformance (DMARC). So, be sure to set up DMARC on your server. This protocol allows you to signify whether you want to reject, quarantine, or deliver emails that fail SPF and DKIM validation.

While much of the above takes place between the sending and receiving server, there’s another layer that helps recipients authenticate themselves, and that’s Brand Indicators for Message Identification (BIMI). With a published BIMI record, you can display your logo on authenticated email messages. This allows recipients to confirm authenticity with a glance.

2. Build and Maintain a Clean Email List

A clean email list begins with how you acquire subscribers. When building an email list, make sure to:

Collect high-quality contacts. You can do this by putting your sign-up forms in places like your website and social channels. These are online spaces where visitors have shown a level of interest in your business.
Verify email addresses. You can do this by checking email address syntax, removing contacts with a universal recipient address, or pinging the mail server to see if the email is active.
Use double opt-in to ensure that anyone signing up is truly interested in your business.
Allow your subscribers the option to reduce the number of emails they receive or to unsubscribe permanently.

Then as your list grows, clean regularly. But how often?

"I would say as often as needed," recommends Vince Cersosimo, Co-Founder of Webbula. "First, you always want to start with an initial cleanup. Run it through, identify, score and segment your list, and based on your risk tolerance take the good stuff and move forward. Then you want to implement a service like Webbula for their email hygiene verification in the form."

He continues, "So as you have users signing up you could be cleaning them in real-time via an API and then periodically thereafter. Watch your deliverability and if you see some aging addresses and deliverability issues start to creep in, then it’s time to pull the list, reprocess it and clean it up."

3. Personalize Your Emails

Personalized marketing emails translates to more email engagement, leading to an uptick in metrics like open and click-through rates. And statistics back this up.

According to Dynamic Yield, 71% of consumers say personalized experiences influence their decision to interact with emails. This increased engagement signifies value to the servers, helping you avoid spam complaints and keeping the bounce rate low.

How do you personalize your email?

First, you need to know your audience. This involves digging into the data to understand user behaviors and pain points. Next, segment your audience based on common factors like geography, interest in specific products, downloaded content, type of last purchase, and page visited.
Use any of the above factors to generate a personalized and dynamic subject line for each segment. For example: “Welcome back, [First Name]! Here’s a fresh playlist inspired by your recent favorites.”
Ensure that the email body follows the subject line, customized based on the preferences of the recipient.
Use dynamic content. It allows you to send the same email to different recipients but slightly altered to resonate with both segments.
Where necessary, link to personalized landing pages. For example, imagine a customer who regularly flies a specific route and you want to recommend lower fares for a specific season. You want to ensure the landing page they visit shows fares from their location.

Remember to integrate your email with your CRM. “In my opinion, the use of a CRM is a very important factor,” says Paulo Moreira, Customer Success Manager at OmniK. “With it, you will be able to create the best possible segmentations, in addition to contacting customers in the best channels for each of them and offering what they want at the right time.”

4. Avoid Spam Trigger Words

Spam trigger words are often caught by spam filters. And it’s not just the filters. People recognize them too and it can be off-putting. They may either delete your email, unsubscribe or report it as spam. Either way, your sender's reputation and deliverability take a hit.

So, what are spam trigger words?

They're words and phrases that focus too much on hard selling instead of providing value. Here are some examples to give you a general idea:

% off
Guaranteed
Free
Giveaway
Exclusive deal
To whom it may concern
Act now
Link inside
Buy now
Earn $$$
Urgent action needed
Money

Notice that some of these are words and phrases you’ll need in certain contexts and yet they can be flagged as spammy language.

The trick to beating this is to pay attention to the context and use the words as naturally as possible if you have to. Spam filters are sophisticated enough to understand the context. So, instead of “Don’t miss out! Your favorite [Product] is 20% off until midnight. Act urgently!” Use “New arrivals: Get your favorite handpicked décor with free delivery until midnight.”

In the second example, the value and offer are clear enough to provide sufficient context. With that, your emails should arrive in your recipient’s inbox. It also helps to send emails without typos and to have a good sender reputation already in place.

5. Optimize Subject Lines and Preheaders

Your subject line, and the preheader that appears below or beside it, are the first visible aspects in the email preview. With both, you want to keep it relevant and enticing. Here are some tips to help you optimize them:

Keep your subject lines and preheaders short for the most impact. Headers should be between 40 to 80 characters.
Summarize the body of the email in your preheader when possible. When not, offer an incentive or highlight benefits.
Create urgency or curiosity in your preheaders without resorting to spammy words.
Put your offers at the beginning of the subject line.
Include the subscriber name in the subject line for personalization.
Consider the best capitalization style for you. People tend to appreciate the casual for a personal feel, so I recommend using a sentence case.
A/B test to evaluate which version works for your target audience.

Overall, don’t try to be vaguely creative or clever. You want to be clear while grabbing the reader’s attention.

6. Limit Links and Attachments

Attachments can be useful in your email, but they come with some downsides. They tend to affect deliverability because filters treat them as spam. Deepali Sing l a, Test Engineer at Infosys, recommends the following strategies to help keep your emails clean and effective:

Assess Necessity: Before attaching a file, determine if its content can be summarized within the email body to maintain clarity.
Use Descriptive File Names: Assign meaningful names to attachments that reflect their content, aiding recipients in understanding their relevance.
Mention Attachments Clearly: Reference attachments in both the subject line and body of the email, explaining their importance and contents.
Opt for Links Over Attachments: When feasible, include hyperlinks to documents instead of attaching files. This approach reduces email size and minimizes the risk of being flagged as spam.

Generally, you just don’t want to flood your recipients with too much information. If you must include attachments, ensure that they trust your brand and the value you’re providing.

7. Use Deliverability Tools and Spam Checkers

These spam testing tools assess your emails against spam filter terms and standards. They scan your email content to check spam trigger phrases and test your sender reputation.

The more sophisticated tools go deeper than that to perform deliverability checks. They analyze your domain to see if it’s on any blacklist and also examine the robustness of your authentication programs such as DKIM, SPF, and DMARC.

Here are some pre-sending diagnostics tools to help keep your emails away from the junk folder:

Mailtrap
MxToolBox
Mail Tester
SpamCheck
GlockApps

8. Monitor Your Email Metrics and Optimize for Better Performance

Monitoring your email metrics enables you to see how your recipients are interacting with your email campaign. This gives you insights into what’s working and what’s not. There are a lot of KPIs to track, but here are some major ones:

Open Rate: This tells you the percentage of recipients who opened your email. Your subject line has a significant bearing on your open rate.
Click-Through Rate: This shows the percentage of people who clicked a link in your email. It’s indicative of content effectiveness.
Conversion Rate: This tracks the percentage of people who completed a desired action, like purchasing a product or filling out a form. Your CTA is key to higher conversion rates.
Spam Complaints: This tells you the percentage of subscribers who reported your emails as spam. This indicates that the receiver found your email unwanted or intrusive.
Bounce Rate: This metric measures the percentage of emails that didn’t deliver out of the total email you sent. This could be a hard or soft bounce. Soft bounces, often temporary, happen when the recipient's inbox is full or their server is faulty. While hard bounces result from nonexistent or invalid email addresses.

Keep Your Emails Out Of Spam And Boost Engagement

Remember, small tweaks to your email marketing strategy can make a big difference in improving deliverability and ensuring your messages get seen—and acted on.

And by now, you’ve got a good understanding of how spam filters work, why emails go to spam, and the steps you can take to avoid it. With insights into writing authentic, engaging emails and maintaining a strong sender reputation, you’re better equipped to not only get your emails to your recipients’ inboxes but also to increase engagement and drive better results for your email campaign.