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  • Writer's pictureTanya S

Improve email marketing effectiveness by reducing spam rate

Running a small business in 2023 is no easy task considering the steep competition for your customer's attention. Consumers could allocate only a certain amount of time and attention. Knowing that, how do you keep your audience engaged and loyal customers? How do you ensure you capture their attention when you communicate with them? Today, we will discuss reducing your email marketing spam rate and increasing deliverability to keep your customers engaged and increase sales.

You need to know that nearly half of all emails are spam which means there's a good chance some of the emails you're sending to your customers are spam. Initially, it's challenging to grasp why your emails hit spam filters because it's unseen, and it is not common knowledge about how email filters work.

We know emails that end up as spam are costly to your business and could damage your reputation. We've worked with many companies and heard their horror stories about how they've wasted their precious time and resources getting emails into inboxes but struggle to do so. A few best practices and understanding how email spam works can do wonders for your business communications. Let's find out what you can do to avoid your emails from landing in spam.

Why do emails go to spam?

The most obvious and straightforward answer: recipients put emails there.

Even if you share relevant, helpful content and have explicit permission to contact them, recipients can still mark your email spam. They may be organizing and cleaning up a cluttered inbox, may have forgotten you, or just made a mistake. Spam filters are pretty intuitive and observe every email activity. When recipients flag some of your messages, all future emails are automatically filtered as spam.

Worse, AI-driven algorithms behind automatic anti-spam filters on popular email services like Gmail, Outlook, and Yahoo collect data for improvements. Your emails can look spam even to somebody who hasn't flagged them.

Here are the reasons we noticed emails would go to spam:

  • Misleading or inaccurate sender information: The "From" line in your emails tells recipients who sent the message. If your sender information contains random characters or a series of numbers, your emails look unprofessional, automated, and suspicious, and recipients may flag them as spam.

  • Misleading subject lines. Recipients usually mark emails with deceptive clickbaity subject lines as spam, if not the spam filters themselves. This affects your domain's reputation. For example, you're offering a vacation deal, but your email subject line says, "30% off guaranteed. Buy now!" It doesn't specify the offering and will likely be flagged as spam.

  • Email domain with a poor reputation. Your domain reputation affects email deliverability. Think of it like an email credit score with a public backlist shared between email service providers (ESPs). Too many recipients marking your email spam impacts your domain's authority. Emails from a bad domain skip the recipient's inbox and go to the spam folder.

  • Lack of proper authentication. Email authentication protocols verify and filter emails originating from your work email domain ( These protocols typically mark messages from unauthenticated email domains as spam.

  • They are using words that are spam triggers. Spam filters scan incoming emails for words spammers love: 50% free, no cost, bonus, easy money, buy now, offer expires, and so on. Excessive "sales" language, too many exclamation marks (!!!!!!), and even writing in CAPITAL LETTERS can trigger spam filters.

  • Their emails were linked to shady or misleading websites. Using the wrong links in your emails will get you into trouble. Email scams and phishing attacks often link to malware-infested websites, so spam filters always look for shady links. Spam filters built into popular ESPs look for misleading links that display a URL, take you to an unknown destination, and flag them as spam.

  • They were sending too many attachments. Attachments are a big red flag for spam filters, especially if you add too many. Emails with too many attachments are unlikely to reach recipients' inboxes.

How spam filters work

While you can't stop recipients from accidentally marking your email spam, you can minimize activating spam filters if you know what they look for in emails.

  • Quality content

  • A professional email address

  • Segmented audience

  • Clean mailing list

Spam filters attack emails to protect recipients from malicious cyber attacks. In reaction to the advancement in email fraud and phishing attacks, advances in artificial intelligence (AI) and machine learning (ML) have made modern spam filters more sophisticated and precise.

Spam filters come in various forms, each with unique criteria to inspect emails and block unsolicited messages. But they all work similarly – scan email headers for malicious information, block known spammers (blacklists), and scan content for patterns that indicate phishing attacks. It's equal parts science and art.

Types of spam filters

Popular email services like Gmail and Outlook have built-in spam protection. Still, security-conscious professionals and businesses implement gateway (on-premises), desktop-based, or cloud email spam filters for better protection.

There are three spam filter categories based on how they scan emails and identify spam messages: header, content, and list-based filtering.

Header filters

Header filters evaluate the information in the email header for suspicious details or activity. This involves checking the sender and recipient details, subject line, and email relay chain. An email relay chain is a trail left by the servers involved in email delivery. Spammers typically fake this trail because they don't want to be tracked.

Content filters

Content filters scan incoming emails for a predefined list of words (free, easy money, 100% guaranteed, and more) that spammers use. Anyone can customize these filters and add their own spam trigger words.

Heuristic filters are also content-based. They use algorithms to identify spam by rating specific words and phrases in your emails. Suspicious words and phrases in a message are given a higher score than other terms. Your email becomes spam if the total score exceeds a predefined threshold.

Bayesian filters are one of the most advanced spam filtering systems. These rule-based filters use mathematical formulas to analyze a new message's content and compare it to previous emails from the same sender. They assess the overall context of emails. Bayesian filters learn over time and become significantly more accurate at distinguishing valid and spam emails.

Blacklist filters

Blacklist filters are pretty straightforward. They compare the sender's domain name or IP address to a blacklist of bad-reputation email domains – domains that are known to send suspicious emails or have previously been flagged by recipients) and move it with similar emails to the spam folder. Most email service providers allow you to blacklist specific email addresses.

Methods to keep your emails out of spam

Once you know how spam filters work and why your email is spamming, you can implement effective strategies to keep your emails out of the spam folder.

Use a professional email address

When you get a business email from someone you don't know or don't immediately recognize, you probably move it to trash or report it as spam. Your recipients will do this if your email address is suspicious or contains gibberish.

Using a professional email address is the first step in building customer trust. In addition to branding, a business mailbox gives your email legitimacy, letting customers know they can trust the email's source. If you have any follow-up emails to send, ensure to use the same address. This way, they know it's a valid message from a company, even if they don't immediately recognize the sender, so your message is less likely to be marked as spam.

Provide your recipients a choice to unsubscribe

Marketing emails should provide recipients with a straightforward way to unsubscribe. It's not a legal requirement everywhere, but ESPs consider an unsubscribe option a critical feature of legitimate email.

Allow your recipients to easily unsubscribe by including an unsubscribe link in the email header or footer. Additionally, delete emails of recipients who unsubscribe from your mailing list. You can even automate this process using a professional email service.

Clean up your mailing list(s)

A clean, up-to-date mailing list keeps engagement high and un-subscribe rates low. Your email campaigns will receive fewer soft bounces and spam complaints from uninterested recipients, so the domain's reputation won't suffer. You'll also send fewer emails overall, and many ESPs charge by number, so having a clean mailing list will save you money.

To clean up your mailing list, eliminate duplicates, typos, invalid emails (hard bounces), and spam catchers – email addresses with the word "spam" in them. Ensure each subscriber on the list has opted in to receive your emails. Then segment by demographics, geography, interests, and engagement rates to show how your current audience matches your ideal.

Scheduling a mailing list cleanup is helpful, especially when you have many. Always focus on quality before quantity. Your goal is to ensure everyone on the list wants your email.

You can also consider double opt-ins and opt-outs, so recipients can choose only to receive certain content and implement a sunset policy to remove unengaged subscribers from your mailing list.

Segment your email audience

Email segmentation is about understanding the people you're writing to, knowing where they are in the customer lifecycle, and sharing content they find helpful. Start segmenting your audience based on demographics, location, interests, and acquisition sources if you send weekly or monthly newsletters. Proper segmentation reduces deliverability issues and increases engagement rates.

You may want to segment recipients based on the sales funnel stages and tailor emails to your prospects' needs. Similarly, e-commerce businesses can segment mailing lists based on indicators like cart abandonment, average order value, and purchase history and email customers the right content to buy (or buy again) without intruding and spamming.

Some email marketing service providers allow you to segment audiences based on engagement rates. So, recipients who haven't engaged with your messages as much in the past get fewer emails and are less likely to mark you as spam.

Go for a double opt-in approach

One of the most effective strategies for protecting your business email from spam is to confirm that recipients are genuinely interested in your email. A "double opt-in" approach helps you record subscribers' consent and signal their ESPs that your emails shouldn't be marked as spam.

When someone submits their information on your website, send them a welcome email that requires an action, usually a checkbox or a link to your policies. Subscribers will only be added to your mailing list if they confirm this.

This approach accustoms recipients to open your emails and shows their spam filters that your emails are not unwanted nor unsolicited. You can still ask recipients to save contact information and skip spam filters forever.

Avoid using words and phrases that activate spam filters

You already know how trigger words and phrases in email content dramatically increase spamming rates. They make you sound like a spammer and attract the attention of spam filters. A few trigger words alone might not be enough to flag your message immediately.

But, too many trigger words in the subject line or body text coupled with signals like an unauthenticated mailbox, bad domain reputation, or too many attachments will make your email spam sooner or later.

Add value to every email

A few simple strategies can keep your business emails out of spam filters and win you half the battle. You can win the other half by providing value and ensuring your recipients never reach for the "report spam" button. Implementing the above methods may seem daunting and time-consuming, but investing the time in the early days of sending a business email will help you stay on track and contribute to excellent domain authority and reputation.

Be better safe than sorry. Once your emails end up in spam, starting from scratch becomes a steep climb. Warming up a new email address, sending out emails in small batches, and restoring your domain reputation will take up valuable time that you'd instead invest in growing your business.

Preventing email spamming isn't rocket science. With every email you send, you specify what's in it. Make sure it's relevant, informative, and valuable. Keep it legitimate and non-promotional. You're conversing, not making a transaction, so make emails more personal, not promotional.

You're up against everyone else for a spot in your customers' inboxes, and a well-crafted email can go a long way in building lasting relationships. Now that you know how to avoid being labeled as spam, learn how to write a professional email that gets a response.

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