We understand your concern regarding emails reaching the recipient’s Spam/Junk folder instead of the Inbox. This behavior is controlled entirely by the recipient mail server’s filtering mechanisms, and not by the sending platform once the email has been successfully delivered.


Below is a detailed explanation of the most common reasons and the actions that can be taken to improve inbox placement.


Primary reasons for emails go to spam

1. Sender Reputation

Recipient email servers continuously evaluate the sending IP and domain reputation based on:

  • Past spam complaints

  • Hard bounces and invalid recipients

  • Sudden spikes or irregular sending patterns

If reputation is impacted, emails may be routed to Spam even though they are technically delivered.


2. Authentication Issues (SPF, DKIM, DMARC)

If email authentication is missing, misconfigured, or failing, recipient servers may treat emails as suspicious.

Common issues include:

  • SPF not authorizing the sending IP

  • DKIM signature missing or failing

  • DMARC policy not aligned with SPF/DKIM


3. Email Content & Formatting

Spam filters analyze email content for:

  • Excessive promotional language

  • Spam trigger keywords

  • Overuse of images or links

  • Mismatch between subject and body content

  • URL shorteners or low-reputation links

Poor HTML structure or missing plain-text versions can also impact deliverability.


4.  Low Engagement from Recipients

Mailbox providers track recipient engagement, such as:

  • Opens

  • Replies

  • Deletes without reading

  • Marking emails as spam

Low or negative engagement signals can cause future emails to be delivered to Spam.


5. Recipient-side Policies

Many organizations use advanced security tools such as:

  • Spam gateways

  • DLP filters

  • Anti-phishing engines

These systems may override global mailbox provider rules and place emails in Spam or Quarantine based on internal policies.


6. Missing Whitelisting

If the sender domain or IP is not explicitly trusted by the recipient’s email system, messages may be filtered, especially for corporate domains.


Recommended Actions

a. Authentication & Technical Checks

  • Ensure SPF, DKIM, and DMARC are correctly configured and aligned.

  • Use a consistent sending domain and IP.

b. Content Optimization

  • Avoid spam-trigger words and misleading subject lines.

  • Maintain a good text-to-image ratio.

  • Use clean HTML and include a plain-text version.

  • Ensure all links point to trusted domains.

c. Improve Engagement

  • Send emails only to opt-in recipients.

  • Remove inactive or invalid email addresses regularly.

  • Encourage replies or interactions where appropriate.

d. Recipient-side Actions

  • Ask recipients to mark the email as “Not Spam”.

  • Whitelist the sender domain and IP address.

  • Add the sender address to their contact list.

e. Monitoring & Best Practices

  • Maintain a consistent sending pattern.

  • Gradually ramp up volumes for new domains/IPs.

  • Monitor bounce rates, spam complaints, and engagement metrics.


Please note that, even when emails are technically delivered successfully, final inbox placement is determined solely by the recipient’s mail server. Each provider applies its own proprietary filtering algorithms, which may differ across domains and users.


In case of any further assistance required, feel free to reach out to us on help@netcorecloud.com