The spam folder: every email marketer’s worst nightmare. Why do your emails end up in the spam folder, and is there anything you can do about it?

Fortunately, emails going to the spam folder aren’t a result of bad luck. It signifies an issue that you need to fix. And while that might sound easier said than done (because it is), we’re here to help guide you toward a solution.

Spam‑bound emails aren’t just an inconvenience—they’re frustrating and downright annoying for your customers and subscribers. While they might not mind missing a feature announcement or newsletter here or there, your customers will be frustrated if their two‑factor authentication codes, password resets, or purchase receipts never show up.

Regardless of what you’re sending, let’s help you get it where it belongs. Below, we’ll walk you through a few reasons your emails might be going to the spam folder and what you can do to fix it.

Are my emails spam?

Email spam is unsolicited, unwanted bulk email sent to many recipients without their consent. Your emails might be considered spam if you’re sending unsolicited messages to people who haven’t opted in to receive them, using deceptive subject lines, or sending content that lacks value to recipients.

Sometimes, even legitimate senders can accidentally trigger spam filters by using suspicious formatting, too many links, misleading subject lines, or sending to unengaged lists. That doesn’t necessarily mean your message is spam, but it means you’ll need to make some changes.

Remember, it’s not just about what you consider spam—it’s about how mailbox providers and recipients perceive your messages. If your recipients aren’t engaging with your emails or are marking them as spam, mailbox providers will take notice and adjust your deliverability accordingly.

Why are my emails going to spam?

If your legitimate emails are landing in spam folders, several factors could be responsible. Email service providers use sophisticated filtering algorithms to analyze your sender reputation, authentication methods, content quality, and recipient engagement.

Common triggers include missing or improper email authentication (SPF, DKIM, DMARC), poor sender reputation, low engagement rates, suspicious formatting, triggering content, or unclean email lists with high bounce rates.

The good news is that most deliverability issues can be identified and fixed with the right approach. Understanding why your emails go to spam is the first step toward implementing effective solutions to reach the inbox consistently.

How email spam filters work

Email spam filters determine which emails make it to the inbox and which go to the spam folder. Once you understand how these filters work, you can craft more intentional messages that don’t accidentally trigger their wrath.

Spam filters are sophisticated algorithms email service providers (ESPs) use to protect users from unwanted emails, phishing attempts, and malware. They analyze various aspects of incoming emails (including your sender reputation, content, and metadata) and assign your message a spam score. If your score exceeds a certain threshold, it’s flagged as spam and diverted from the inbox.

• Sender Reputation: If your IP address has been used for spam in the past or is from a domain with a poor reputation, your emails are more likely to be flagged.
• Authentication Protocols: A lack of proper email authentication (like SPF, DKIM, and DMARC) can lead to emails being marked as spam, raising doubts about the sender’s legitimacy.
• Content Quality: Emails with spammy phrases, excessive use of caps, or an abundance of links and images compared to text can trigger spam filters.
• Recipient Interaction: Low engagement rates (like low open and click‑through rates) or a history of recipients marking your emails as spam can influence filtering decisions.
• Inconsistent Sending Patterns: Sudden spikes in email volumes or irregular sending behaviors can be seen as spam‑like activities.

8 reasons why email goes to spam (and what to do about it)

1. Poor sender reputation

Mailbox providers and ESPs use your email sending history to score your domain or IP reputation. This score reflects the trustworthiness of your emails and is influenced by factors like email volume, frequency of emails marked as spam, bounce rates, and engagement metrics.

A poor sender reputation signals to email providers that your emails might not be legitimate or wanted, leading to higher spam filtering rates. If folks aren’t opening your emails (or liking what’s inside), email providers will just send it to email purgatory.

Improving your sender reputation isn’t an overnight process. You’ll need to clean up your list, deliver consistent and relevant content, boost your engagement rates, and avoid sending practices that could flag your emails as spam.

2. Lack of authentication

Email authentication involves setting up protocols like Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain‑based Message Authentication, Reporting, and Conformance (DMARC). These protocols validate your emails, proving to mailbox providers and ESPs that they originate from a legitimate source. These protocols are so important that mailbox providers have started requiring them to be able to send email.

Without proper authentication, your emails are at a higher risk of being flagged as spam or, worse, being used for email spoofing or phishing. Lack of authentication undermines the trust in your emails both from email providers and recipients.

The fix is simple: implement SPF, DKIM, and DMARC for your email domain. Regularly review and update these settings to ensure they align with your current email practices and infrastructure changes.

Want to check your email authentication status? Use our free domain checker: 👉 https://www.palisade.email/tools/email-security-score

3. Content‑related issues

Emails with spammy subject lines, excessive use of sales‑oriented phrases, too many links, or poor HTML coding can trigger spam filters. Overuse of images compared to text and lack of relevancy (read: click‑bait) also contribute to this issue. Even if your sender reputation is solid and your emails are well‑authenticated, poor content can still land your emails in spam.

Focus on creating well‑balanced, relevant, and engaging email content. Avoid spammy phrases and excessive promotion. If it looks like spam, it’s probably going to get marked as spam. Regularly test and review your email content for spam triggers to help maintain high deliverability rates.

4. High complaint rates

Complaint rates refer to the frequency with which recipients mark your emails as spam. High complaint rates are often a direct indicator of how your audience perceives your emails. Factors contributing to high complaint rates include irrelevant content, excessive frequency, or emails sent without proper consent.

When complaint rates rise, mailbox providers and ESPs take notice. High complaint rates can quickly tarnish your sender reputation, leading to more of your emails being filtered into spam.

Prioritize consent‑based marketing to reduce your complaint rates. Make sure your subscribers give explicit consent before sending them any emails. Tailor your content to match subscriber interests and maintain a balanced sending frequency. Implementing a feedback loop can provide real‑time insight into complaints.

5. Mailbox sender requirements

Major email providers (like Google, Microsoft, and Yahoo) have set specific sender requirements to combat spam and protect users. These requirements include authentication protocols, sender reputation management, and content guidelines.

Google, Yahoo, and Microsoft’s new email sending requirements call for senders to set up SPF, DMARC, and DKIM, reduce spam rates, implement one‑click unsubscribes, and more. Failure to follow these guidelines will result in more emails landing in the spam folder or never arriving at all.

6. Email blocklists

Email blocklists are databases of IP addresses and domains known to send spam. Various organizations maintain these lists and provide them to email service providers to help filter out potentially harmful emails. Being on a denylist means more emails will be blocked or sent to the spam folder on multiple email platforms.

Mess up your sending, and you might just find yourself on one of these lists. Monitor your domain or IP regularly using online blocklist‑checking tools to see if it is listed on any deny‑lists. If you find yourself blocklisted, identify the cause and address it promptly.

7. Low engagement rates

Your open and click‑through rates indicate how interested and responsive your subscribers are to your emails. Low engagement rates signal to mailbox providers and ESPs that your recipients aren’t interested in or are disengaged from your content.

Consistently low engagement can lead to mailbox providers categorizing your emails as low‑priority or spam. This is because spam filters increasingly use recipient engagement to determine an email’s relevance and value.

Here are a handful of ways you can boost your engagement rates:

• Clean your list and remove unengaged and inactive recipients
• Boost the quality of your email content
• Change the frequency of your emails
• Consider lowering the volume and focusing on quality over quantity
• Segment your emails to send more targeted and relevant content

8. Inconsistent sending volumes

Sudden spikes or drops in email volume can be a red flag for spam filters. They want to see smooth, consistent sending patterns.

A sudden increase in email volume can signal to ESPs that your account may have been compromised or that you are engaging in spamming activities. This can lead to your emails being filtered into spam folders or your account being temporarily blocked.

Maintain a consistent email‑sending schedule to avoid this issue. Plan your email campaigns ahead of time to spread out your sends and avoid triggering spam filters.

Quick Takeaways

• Spam placement is rarely random—look for authentication, reputation, or content issues.
• Implement SPF, DKIM, and DMARC to prove your identity and avoid spoofing.
• Maintain a clean list and high engagement to protect your sender reputation.
• Follow major mailbox providers’ requirements, including one‑click unsubscribe links.
• Balance text and images; avoid spammy subject lines and excessive promotional language.
• Monitor blocklists and address any listings promptly.
• Keep sending volume steady and scale gradually as your list grows.

Frequently Asked Questions

Why do my emails to Gmail users go to spam?

Gmail applies strict filtering that weighs sender reputation, authentication (SPF, DKIM, DMARC), and user engagement. Missing any of these signals can push your messages into Gmail’s spam folder.

Can switching email service providers fix spam issues?

Changing providers alone won’t solve the problem. Your domain’s reputation and authentication settings travel with you, so you still need to implement proper SPF, DKIM, and DMARC and maintain list hygiene.

How can I test if my emails land in spam without asking recipients?

Use seed testing tools or inbox placement testing services that send emails to test accounts across major providers and report where they land.

Do images cause emails to go to spam?

An imbalanced image‑to‑text ratio can raise spam scores. Aim for a balanced mix and always include descriptive alt text.

Will using a free email domain increase spam risk?

Yes. Free domains lack proper authentication and look less professional for bulk sending, increasing the likelihood of being flagged as spam.

For more on email authentication best practices, check out Palisade’s email authentication guide.