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How to Reduce the Risk of Your Emails Being Marked as Spam?

No one wants their carefully crafted email marketing campaign to end up in the spam folder.

What is the Spam Complaint Rate?​

The spam complaint rate is defined as: Number of complaints ÷ Number of emails delivered

It is one of the most important metrics for measuring email quality.

If your complaint rate is too high, it may result in:

  • Emails being automatically classified as spam
  • Your sending domain or IP being blacklisted
  • Failure to meet the latest sending requirements of Gmail, Yahoo, and other email providers

How to Tell if Emails Are Going to Spam​

Email service providers can usually only tell you whether an email was “successfully delivered,” but not:

  • Whether it landed in the Inbox
  • Or in the Spam folder

To determine the actual delivery folder, you can use these methods:

  • Seed testing
  • Small-scale test sends to real users
  • Third-party delivery monitoring tools

These methods help you analyze inbox placement across different email providers.

Why Emails Go to Spam​

1. Domain and IP Reputation​

Email providers build a Sender Reputation score based on your sending history:

  • Low reputation → much higher chance of landing in spam
  • When using shared IPs, other senders’ behavior can also affect you

2. Spam Complaints​

When users click “Mark as Spam”:

  • It directly harms your sender reputation
  • Increases the probability of future emails going to spam

3. User Engagement​

Email providers track user behavior such as:

  • Whether users open the email
  • Whether they click links
  • Whether they ignore the email

Low engagement signals that:

  • Your emails are unwanted
  • Content quality is low resulting in higher spam placement.

How to Prevent Emails From Going to Spam (10 Methods)​

1. Use a Reliable Email Service Provider (ESP)​

Choosing a reputable email platform will:

  • Provide more stable inbox delivery
  • Help you manage sender reputation

2. Comply with Anti-Spam Regulations​

Ensure your sending follows laws such as:

  • CAN-SPAM (USA)
  • GDPR (Europe)

Core principles:

  • You must have user consent
  • Do not send unsolicited emails

3. Set Up Email Authentication​

You must correctly configure these DNS records:

  • SPF
  • DKIM
  • DMARC

These authentications prove:

  • The email genuinely comes from you
  • It has not been tampered with

4. Use Double Opt-in​

Users confirm their subscription a second time after signing up.

Benefits:

  • Reduces invalid email addresses
  • Improves list quality
  • Lowers complaint rates

5. Encourage Users to Whitelist You​

Prompt users in emails to:

  • Add your sender address to contacts
  • Mark your emails as “Not Spam”

This greatly improves future deliverability.

6. Avoid Spam Traps​

Spam traps are “honeypot emails” set by ISPs to catch spammers:

  • They may be unused or abandoned email addresses

Sending to these addresses:

  • Severely damages your reputation
  • Can lead to blacklisting

7. Send Content Users Actually Want​

Emails must be:

  • Highly relevant
  • Truly valuable

Otherwise users will:

  • Ignore your emails
  • Mark them as spam

8. Clean Your Email List Regularly​

Regularly remove:

  • Invalid email addresses
  • Long-term inactive users

This:

  • Boosts overall engagement
  • Reduces negative signals to ISPs

9. Provide an Easy Unsubscribe Method​

Every email must include:

  • A clear, visible unsubscribe link

Otherwise users are far more likely to:

  • Simply click “Mark as Spam”

10. Optimize Email Content​

Best practices:

  • Avoid typical spam trigger words
  • Control the number of links
  • Keep content professional and clear

Core Insight​

The root cause of emails going to spam is not just technical — it is:

👉 The quality of your relationship with subscribers

Email providers are essentially judging:

  • Whether users want your emails
  • Whether your emails are trustworthy

Therefore, the key to improving deliverability is:

  • Building long-term user trust
  • Delivering consistent value
  • Maintaining a strong sender reputation