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11 reasons why your email goes to spam

Reading Time: 8 minutes

Digital marketers generally spend most of their time perfecting content, but authentication processes and spam filters can prevent readers from even seeing your messages. Many brands aren’t even aware of how many of their messages don’t make it to inboxes and are being filtered out as spam.

Fortunately, there are some easy ways to increase your delivery rate and make sure more emails reach their target inbox. Let’s take a look at a few common reasons why spam filters flag particular emails and go through the best strategies for optimizing deliverability.

Why are my emails going to spam?

Spam filters have been around for a long time, and they’ve gradually grown more complex as spam has become more of an issue. Contemporary filters use several authentication and analysis criteria for every message, so your emails go to spam for a number of reasons. Understanding where you’re going wrong will point you in the right direction to improve your campaigns.

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1. No permission to contact recipients

Spam emails are more prevalent than ever, and sending emails to people who haven’t opted in to your newsletter is a major red flag. In fact, you could be held responsible for as much as $40,000+ in penalties for sending messages without consent.

Use your website to gather good-quality subscribers instead of buying ready-made lists. Paying for email lists full of spam traps is one of the most common reasons why businesses get flagged for emailing without permission. Acquiring such contact lists lead to significant consequences for your company. It could be worse by adopting the wrong email blast strategy along with buying lists.

All of this helps create a unique, engaging ecommerce experience that will keep them coming back for more.

2. Bad sender name

Beyond using a custom domain that’s the same as your official website, use an interesting and relatable sender name. Boring sender names can make readers less interested in your content, while misleading subscribers with your domain and sender name is illegal under the CAN-SPAM Act. So, too, is failing email authentication processes due to phishing and spoofing. In any case, optimizing your sender name is a great way to improve performance and deliverability.

Of course, the CAN-SPAM Act doesn’t require businesses to use the same generic name for every email. You still have a lot of room to experiment with different names for a more personal touch.

For example, you can switch your sender name to your own name, the name of your business, the name of the newsletter, or anything else as long as it accurately represents who the email is coming from. Don’t forget to split-test different sender names to fine-tune your approach.

3. Inactive subscribers

Spam filters are designed to remove content that users aren’t interested in, so it’s no surprise that subscriber activity is one of their main criteria. Businesses struggle with engagement for several reasons, and keeping your email list active is an ongoing effort.

Although collecting emails takes a long time, don’t hesitate to delete inactive ones. They have no value and only spoil your sender reputation score, so there’s really no point in keeping them. There are good practices for removing inactive subscribers correctly.


4. High bounce and complaint rates

A high bounce rate (more than 4%) usually means that the email list is outdated, low quality, or purchased. Email clients (Gmail, Outlook, Yahoo) treat such senders poorly and affect their senders’ reputation.

Most email clients give their users the ability to report emails as spam. Content may be filtered out if too many messages are reported. Ideally, your Complaint rate should be no more than 0.1%, or one in one thousand recipients. Most email marketing platforms automatically record and display this number based on all senders in the same domain

5. Poor image-to-text ratio

When it comes to passing HTML emails through spam filters, there are two aspects that marketers keep debating about: 1. Image-to-text ratio and 2. Spammy words.

Image-to-text ratio is more of a B2B sales emails issue and became irrelevant for retailers once email providers started caching images and displaying them by default. That’s why, at Omnisend, we suggest not worrying about images in promotional newsletters. However, text elements should be included in the HTML email as well, and attachments should be avoided. If your brand language and email content are consistent, spam filters shouldn’t be bothered.

6. Spammy text

Spammy words is another topic worth a discussion. Subject lines containing “free”, “now”, “%”, “hurry” can be determined as spam filter triggers. But these words are vital for ecommerce emails—they are actionable and create scarcity. Check your inbox, there are plenty of emails with these words. So why didn’t they trigger the spam filter, and how did they get into your inbox?

At Omnisend, we don’t think that spammy words alone can harm your email deliverability. But we agree that multiple exclamation signs and all-caps text in subject lines can look spammy, and marketers should write actionable and compelling subject lines without using these signs.

7. No address or unsubscribe option

Physical addresses and unsubscribe buttons are two more areas in which spam regulations have gotten substantially stricter. Even if you avoid a fine, omitting either of these two will almost certainly hurt your delivery rate.

Not including an address is a particularly common mistake as small business owners may not be aware of the requirement. If you’re apprehensive about including your personal address in every email, you can always get a PO box and list that instead.

Similarly, your unsubscribe button needs to be conspicuous and easy to access. Underhanded tactics such as nearly invisible fonts, long unsubscribe forms, and empty space before the unsubscribe link will only backfire.

Readers shouldn’t experience any hangups when attempting to unsubscribe.

8. Overly frequent campaigns

During the last Black Friday, I received eight different emails from the same domain, which means they were all from the same brand.

Without mercy, I reported them as spam. Even though I was interested in the brand’s communication, receiving so many messages in one day was simply too much even for an email maniac such as myself. Some even contained attachments, which added to the aggravation.

The moral here is simple: your subscribers shouldn’t be overwhelmed by receiving too many emails from you.

The ideal email frequency is 2-3 times per week. For daily senders: no more than once a day.

9. A sudden increase in the number of email messages sent

If a brand is typically sending to 10,000 subscribers and suddenly starts sending to 200,000, this spike will trigger spam folders (because email clients consider spikes as unexpected behavior and spam attack).

If you want to increase your contact list size, do that gradually.

10. Switching email service providers

Every switch of ESP makes an impact on your sender reputation score. Every time after changing your email marketing tool, you need to warm up your domain’s new sender reputation so email clients won’t identify you as a spammer.

11. Blacklisted IP address

Fixing these problems is usually enough to fail email authentication processes and avoid spam filters, but you may still have trouble reaching your target deliverability. In some cases, a sender’s IP address can negatively affect deliverability even after they’ve addressed all other issues.

Checking your IP’s status is surprisingly easy. MX Toolbox and similar services can check your IP against some of the most popular blacklists. While no search engine can cover every possible blacklist, this is a great place to start if you’re still not sure what’s responsible for your low deliverability.

Most reputable email marketing services have safeguards in place to avoid this problem, but there’s always a chance that your platform has been flagged by spam filters. Small email marketing companies are more likely to be unreliable as they don’t have as many resources to combat spam filters.

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How to prevent email from going to spam

Now that you know some of the reasons why emails go to spam, you can start adjusting your own practices to maximize deliverability and make sure any message will actually make it to the inbox. This section will cover some of the best places to start if you’re looking for ways to stop emails from going to spam.

1. Give subscribers what they want

Sending too much, too little, and too generic content are three of the top factors leading to unsubscribes and poor deliverability. Unfortunately, every subscriber has their unique preferences, so improving deliverability isn’t as simple as finding the ‘right’ frequency.

Instead, you should consider giving readers more control over their own subscriptions. You can implement this by adding some options to your subscription form. So your new subscribers could choose what products they are most interested in.

Segmenting your customers and sending the most relevant content to different segments also helps minimize the number of emails going to spam.

2. Implement the sender’s warm-up process

This practice is the most needed when you’re switching your email service provider. Here’s how it improves your sender reputation when compared to sending emails to all your subscribers without a warm-up:

Sender's warm-up process

Want to learn how to avoid spam filters and maintain your smooth transition to better email deliverability? Read our in-depth guide.

3. Make sure your email is wanted

This means that the subscriber explicitly agreed to receive your promotional messages via email. That’s why lists must be opt-in and preferably GDPR-compliant.

The best way to achieve this is to put the sentence of consent in your sign-up form. See an example below:


4. Gradually increase sending volume

As already discussed, if you have hundreds of thousands of emails on your list, starting your email marketing by sending a campaign to all of them at once is a bad idea.

Here’s an example of a gradual warm-up process:

IP warming schedule for a business with 300,000 contacts in total

5. Keep your contact list clean

30% of subscribers change email addresses once per year. If nearly a third of your email list changes their address per year, it means that you should do contact list hygiene periodically, lest you send to nonexistent or inactive addresses.

If someone hasn’t clicked on your emails in the last 12 months, that subscriber should be treated as inactive and unsubscribed from your email marketing.

Such emails might later become spam traps and harm your reputation.

Pro tip: When you migrate from one ESP to another, at first migrate your best contacts who are actively engaging with your emails and start sending only to them.
That way, you’ll gradually transfer your good reputation from one email service provider to another.
After a while, you can migrate the rest of your contact list.
Once again, migrate gradually. Start with a small list, then grow the number of email recipients.

Want to keep your contact list clean the easy way? Omnisend offers a quick and simple email list cleaning service. Our email marketing platform has a free list health check to gauge the percentage of risky contacts, and uses sending and delivery data from Mailgun, which performs bulk validation and grammar checks on email domains across databases of billions of emails.

Here’s an example:

Email list cleaning using Omnisend
Omnisend contact list cleaning example

At the end of the day, email deliverability is a complex issue with multiple components. Only following best email marketing practices and being patient can help you avoid the spam folder.

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Article by
Karolina Petraškienė

Karolina is a writer, content marketer, and email enthusiast at Omnisend. When she's not curating articles, you can find her in the woods challenging herself in hiking boots or off-roading her bike.

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