Spam folders are useful to filter out irrelevant emails from inbox clutter. However, for email marketers, having emails end up in the spam folder poses a significant challenge, as they often go unnoticed by the intended recipients. If your emails are being delivered to your recipients' spam folders, there could be several reasons behind it.

What is a spam filter and how does it work?

Spam filters are software programs designed by Internet Service Providers (ISPs) and webmails to sort incoming emails as either spam or legitimate. Every time you send an email, it goes through these filters before it can land in the recipient’s inbox. This is to protect users from unwanted or risky emails, such as spamming or phishing. 

ISPs and webmail providers determine the placement of incoming emails—whether they belong in the inbox or the spam folder—based on various factors, each following its own set of rules. This means that emails that land in the spam folder on one platform, such as Outlook, may not necessarily be flagged as spam on others like Yahoo or Gmail.

Spam filters assess emails based on several factors, such as:

If an email meets the criteria set by the spam filter, it's marked as spam and directed to the recipient's spam folder.

Reasons why your emails might be delivered to the spam folder

There are many reasons why emails might end up in the spam folder. Understanding these reasons will help you improve your email deliverability, ensuring that your messages reach their intended recipients.

🔓 Your domain isn't properly authenticated

One of the main reasons your emails might end up in spam is because your domain isn't authenticated. When you authenticate your domain, ISPs and webmails can confirm that your emails are legitimate and from your business. Without this authentication, they can't distinguish your emails from those sent by spammers, so they may deliver them to spam folders to protect your recipients.

➡️ To learn more, check our dedicated articles What is domain authentication? and Authenticate your domain with Brevo.

🗑️ Your recipients marked your emails as spam

If your emails are regularly marked as spam by your recipients, ISPs and webmails may automatically filter your emails into the spam folder. To prevent this, ensure that your recipients are anticipating your emails and that your content provides genuine value. They will be eager to open your emails and look forward to receiving more.

🧹 You haven't cleaned your contact list

Over time, some contacts may lose interest or update their email addresses, and there could be typos or nonexistent addresses in your list. Sending emails to these contacts increases the risk of being flagged as a spammer and ending up in the spam folder. Regularly identifying and blocklisting these contacts can improve your email delivery rates.

➡️ To learn more, check our dedicated article Optimize and clean your contact list to improve email deliverability.

❌ Your contacts have not consented to receive your emails

In email marketing, the top rule is to always obtain permission before sending an email. Buying, renting, or acquiring email addresses through unscrupulous methods is strictly prohibited. Emails sent to these addresses will likely end up in spam, and it could lead to the suspension of your Brevo account as it violates our Terms of Use and best practices.

➡️ To learn more, check our dedicated article Build a legitimate contacts database for optimal deliverability and compliance.

🎯 You aren't targeting the right contacts

When sending emails, it's crucial to reach out to contacts who are genuinely interested in your content and likely to engage with it. That's why you should avoid sending emails to your entire contact list. Instead, segment your recipients based on specific criteria, such as their past engagement with your emails or their interest in particular topics. This targeted approach ensures that your emails are more relevant and effective.

👎 Your contacts are not engaging with your emails

ISPs and webmails have stated that they consider the engagement of your contacts with your emails as a factor in spam filtering decisions. This means that if your emails are not opened or clicked, spam filters might assume they’re not wanted or relevant, possibly sending them to the spam folder. To prevent this, make sure you regularly clean your contact list and send content that is relevant to your recipients.

➡️ To learn more, check our dedicated article Optimize and clean your contact list to improve email deliverability.

🆓 You are using a free email address

Free email addresses are ideal for casual conversations with friends, family, or personal contacts. However, if you use a free email address for business-related emails, they're likely to be flagged as spam. Using a professional email address not only makes your communications appear professional and secure but also increases the chances of your emails reaching the inbox.

➡️ To learn more, check our dedicated article Why you need to replace your free email address with a professional one.

🔗 You are using URL shorteners

Always include complete links in your emails as spammers often use link shortening services like bit.ly to hide their original URLs. Also, ensure that any link displayed to users directly, like http://mywebsite.com/products, leads to the intended page and doesn't redirect elsewhere, such as http://mywebsite.com/sales. For the clickable text, it's best to use phrases like "click here," a short descriptive sentence, or a button.

📁 You are including attachments

Including attachments in your emails can sometimes trigger spam filters, especially you send many or if they are large in size. This is because this technic is often employed by individuals looking to send malware or viruses. Be careful when sending attachments, particularly to new subscribers or recipients. Instead of attachments, consider including links to download files from a reputable source or cloud storage.

⚠️ You are using spam trigger words

Surprisingly, the impact of spam words on inbox placement has decreased significantly. While they may have been influential in the past, modern anti-spam engines used by webmail services are far more advanced and are trained with machine learning and AI. However, it's important to note that avoiding spam words alone doesn't guarantee your emails won't end up in the spam folder.

📝 Your IP address or domain has been blocklisted

If your emails are landing in spam folders, it could indicate that your IP address or domain has been blocklisted by an ISP or anti-spam solution. This means your emails may have been flagged and reported on a blocklist because you are suspected of suspicious activities, such as spamming or phishing.

➡️ To learn more, check our dedicated article Why is my IP address or domain name blocklisted?.

🖼️ Your email only contains an image

Sending an email with just an image can cause delivery issues. It's better to create emails with both text and images, rather than just using one image. But don't think that sending plain text emails is always better. Try to mix things up with a good mix of images and text. Also, make sure your images aren't too big, as this can also cause problems with spam filters.

🕑  You are not sending consistently 

It's important to find the right sending frequency. Sending too many emails in a short time or inconsistently can trigger spam filters. As a rule of thumb, you should contact your subscribers a few times a week. However, the ideal frequency varies depending on your relationship with your contacts and the type of content you offer.

🔥 You did not warm up your dedicated IP address properly

ISPs and webmails watch sender behavior closely to prevent spam and ensure legitimate emails reach inboxes. Starting with a new dedicated IP or after a long break means a fresh reputation. This means that ISPs and webmails won't know if you're a spammer and will be looking closely at your sendings. Warming up your IP is therefore crucial to help build a positive sender reputation and reduce the chance of your emails going to spam.

➡️ To learn more, check our dedicated article Warm up your dedicated IP and Best practices for managing a dedicated IP.

How to avoid the spam folder

To increase the chances of your emails reaching your recipients' inboxes instead of their spam folders, you need to follow email best practices. This involves authenticating your domain, sending emails only to contacts who have consented, and customizing your content for your audience. Additionally, you need to keep your emails engaging to encourage recipients to open and engage with them.

➡️ To learn more, check our dedicated article Best practices for email deliverability.

🤔 Have a question?

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