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Aneta Koreba
Written by Aneta Koreba

Why do my emails end up in the spam folder?

Find out the why your emails go to the spam folder and reduce the chances of that happening

It's important to have high delivery results in order to reach the maximum number of users. Know why emails get marked as spam and find out ways to avoid this.

Each Internet service provider (ISP) uses different spam filtering techniques. You can’t predict all of them, but this article will cover some of the most common. Be aware of them, and take them into consideration.

How do Spam Filters Work?


  1. Spam filters want to find out if you really know who the recipient is. There is a high probability that your email will be filtered if you send it to a user’s email address and not to his or her name.
  2. Being on a user’s contact list also plays an important role. We recommend you ask your users to add you to their list of contacts.
  3. Send from a domain that has a good reputation and a good mailing history. Free email addresses (for example, Gmail) get filtered more often than verified domains. Even private domains can have a “poor email reputation”. Furthermore, we don't recommend using a new domain for sending a large number of emails for the first time. As for, we use EmailLabs as our default SMTP provider.
  4. Avoid sending from a no-reply address.


  1. The content of the email campaign should be relevant, clear and well-targeted. Some ISPs are strict when it comes to specific topics, images and links. Send well-tailored content to interested users only.
  2. Maintain a good text-to-image ratio.
  3. Use double opt-ins (a preliminary email with an activation link). Make sure the link(s) you include is valid.
  4. Avoid including code snippets in your messages.
  5. When including links, don't use full URLs. Instead, use absolute paths.
  6. Avoid spam-trigger words: won, order now, click here, etc.
  7. Don't close with "Please do not reply to this email ..." Two-way communication is important to providers.

IP Address

If someone sends spam from the same IP address you'd like to send the campaign from then the probability of your emails being filtered is extremely high. The same happens if you send spam. So, if you send email campaigns from the default SMTP, please, remember that the result can influence all our other clients. We're constantly monitoring the situation. If your spam indicators are high, you will be blocked. For us, it's very important to have a good email reputation.

An IP address can be negatively affected for any of the following reasons:

  1. Presence on a blacklist
  2. High number of user complaints
  3. High number of messages filtered to the spam/junk folder
  4. High number of hard bounces (rejections due to an internal security policy, anti-spam filter or blacklist
  5. High number of messages sent to non-existent or wrong email addresses
  6. Sudden increase in mail volume
  7. Auto creation of messages (Filters analyze content by scanning emails: subject lines, headers, footers, code, HTML tags, images, text color, time stamp, URLs, text-to-image ratio, attachments, and more.)
  8. Recipient's reaction: deleting emails without reading them, sending them to the spam or junk folder

Prevent emails from getting filtered as spam

  1. Send email campaigns only to users who are interested in receiving the info from you.
  2. Remove inactive contacts and avoid ‘spam traps’. The open rate shows your users’ engagement. If the open rate is low, the ISP is more likely to treat your messages as spam.
  3. Always include unsubscribe links to your email messages.
  4. Send email campaigns to trusted users only. does not tolerate the use of purchased or rented mailing lists.
  5. Send targeted and personalized emails. This will help you avoid spam filters and will also positively influence customer satisfaction. You can use a event trigger to narrow down the target audience and reach only the users who are truly interested in the info.
  6. Conduct tests. We highly recommend you test your email campaigns before sending them to a large number of users. (Also, run your tests with various subject lines.)
  7. Keep your subject lines short and personalized. Avoid all caps, colored text, and spam phases such as: won, offer, order now, click here, etc.
  8. Maintain a regular sending cadence. Avoid any sudden increase in mail volume.
  9. Use CAPTCHA (a program designed to differentiate human users from machines) to confirm subscriptions.

The tips in this article will help you send personalized, high-quality email campaigns and minimize the risk of them ending up in the spam folder.