As an email marketer, finding out that your carefully crafted emails are landing in the recipients' spam folders can be frustrating. Understanding the reasons and working to avoid them can greatly enhance your email deliverability and engagement rates. This guide will provide comprehensive information on why emails end up in the spam folder and offer solutions to avoid it.

Understanding Email Deliverability

Before you can work on improving your email deliverability, it's important to understand how it works. Inbox providers (e.g., Gmail, Yahoo) have built-in systems that scan incoming emails. They use complex algorithms to automatically sort these emails into appropriate folders, including the spam folder. Unfortunately, these algorithms are not made public, and inbox providers do not report the specific reason an email was placed into spam.

However, there are some common triggers which, when identified and eliminated, can reduce the chances of your emails landing in the spam folder.

Email Content

The content of your email plays a crucial role in determining whether your email gets delivered to the inbox or lands in the spam folder. There are several aspects of email content that email providers consider when filtering for spam. Here are some things to keep in mind:

Subject Line

The subject line is the first thing your recipient sees and plays a significant role in spam filtering. Here are a few tips for creating subject lines that won't trigger spam filters:

  • Avoid 'spammy' language: Phrases like "act now", "limited time", or "free" can trigger spam filters. Keep your language neutral and relevant to your content.
  • Don't use all capital letters: A subject line in ALL CAPS can seem like you're shouting at your recipients and can trigger spam filters.
  • Don't overuse symbols or special characters: Excessive use of symbols or special characters (!, $, %, etc.) in your subject line can make your email look suspicious.

Text-to-Image Ratio

Having a balance between text and images in your email is important for avoiding spam filters. Here's how:

  • Don't rely solely on images: Spammers often use images to hide their text from spam filters. So, if your email is image-heavy, it might be flagged as spam.
  • Aim for a balance: As a rule of thumb, your email should have at least a 60:40 text-to-image ratio.


Using too many hyperlinks in your email can also trigger spam filters. To avoid this:

  • Limit your use of links: Use only necessary links and try not to include multiple links to the same destination.
  • Avoid URL shorteners: Spam filters can be suspicious of short URLs as they can be used to hide the real destination.

Optimize HTML & CSS Code

The underlying code of your email is another factor that spam filters consider. Here's how to ensure your code is clean:

  • Avoid unnecessary tags or elements: Extra tags, especially in the head of your email, can trigger spam filters.
  • Keep your code clean: If you're using an HTML editor, make sure you're not leaving any unclosed tags or using deprecated HTML elements.


Personalizing your emails can make them appear more legitimate and less likely to be flagged as spam:

  • Use recipient's name: If possible, include the recipient's name in the email to add a personal touch.
  • Segment your audience: Send targeted emails based on your audience's interests and behavior.

Unsubscribe Links

Including an easy-to-find unsubscribe link in your email is not just good practice; it's required by law in many regions. This can help you avoid being marked as spam:

  • Make it easy to find: Include an unsubscribe link at the top and bottom of your email.
  • Respect the user's choice: If a user chooses to unsubscribe, remove them from your list promptly.

By optimizing your email content based on these guidelines, you can significantly decrease the chances of your emails being marked as spam. Remember, the goal is to provide valuable and relevant content to your recipients in a user-friendly format.

Email Authentication Issues

Email authentication protocols are used by mail servers to verify that incoming emails are from legitimate senders. The three most commonly used standards are SPF, DKIM, and DMARC. Failing to meet these standards can result in your emails being placed in the spam folder. Therefore, it is important to make sure your brand is using a valid DMARC policy and that your emails are DMARC compliant.

Sender Reputation

Your sender reputation, also known as your email sender score, is a critical factor in determining whether your emails land in your recipient's inbox or spam folder. Email providers assess this score to gauge the trustworthiness of an email sender. The reputation score can range from 0 to 100, with higher scores indicating a more reliable sender. Several variables can influence this score, including:

Engagement Rates

Engagement refers to how your recipients interact with your emails. High open rates and click rates suggest that your emails are valuable to your recipients, which positively influences your sender reputation. Here are a few tips to boost engagement:

  • Personalize your emails: Use recipient's names, include content relevant to them, and segment your mailing list for targeted messaging.
  • Create compelling subject lines: A catchy and relevant subject line can significantly improve your open rates.
  • Include clear call-to-actions (CTAs): Guide your recipients on what to do next with compelling CTAs.

Sending Volume and Frequency

Sending a large number of emails at once or sending too frequently can trigger email providers' spam filters. To manage your sending volume and frequency:

  • Send emails at a steady rate: Sudden spikes in email volume can be viewed as suspicious activity by email providers.
  • Stick to a consistent schedule: Regularly sending emails at expected intervals can enhance your sender reputation.
  • Segment your audience: Send targeted emails to smaller groups rather than mass emailing everyone in your contact list.

Bounce Rates

Email bounce rates refer to the percentage of sent emails that cannot be delivered. Bounces can be categorized into two types: 'Hard' bounces occur when delivery is attempted to an invalid, closed, or nonexistent email address. 'Soft' bounces occur when the email address is valid, but the email is turned away before it reaches the recipient. Here's how to keep your bounce rates low:

  • Regularly clean your email list: Remove email addresses that lead to hard bounces.
  • Use a double opt-in process: This ensures that subscribers are providing valid email addresses.

Spam Complaints

If recipients mark your emails as spam, it negatively affects your sender reputation. It's important to ensure your emails are relevant and wanted by the recipients. Here's how:

  • Provide value: Ensure your content is useful to the recipient.
  • Don't mislead: Make sure your email's subject line accurately represents the content.
  • Make it easy to unsubscribe: If a recipient wants to stop receiving your emails, make the process straightforward to avoid them marking you as spam.

Unsubscribe Rates

A high unsubscribe rate can negatively impact your sender reputation. If many recipients are unsubscribing, it indicates that your emails may not be providing value. To keep unsubscribe rates low:

  • Provide valuable content: Understand your audience's needs and preferences and tailor your content accordingly.
  • Don't overload your subscribers: Sending too many emails can lead to fatigue and cause subscribers to unsubscribe.

By maintaining good sender reputation metrics, you're less likely to have your emails land in the spam folder. Monitor these factors regularly and take necessary actions to maintain a healthy sender score and improve your email deliverability.


Understanding why your emails are being placed in the spam folder is the first step towards improving your email deliverability. By following the guidelines provided in this guide, you can effectively reduce the chances of your emails landing in spam and improve your email engagement rates.

Remember, the key is to monitor your performance consistently, understand the issues you are facing, and take corrective actions when necessary. Your email marketing efforts will be rewarded with better open rates and click-through rates, leading to more conversions.