Manoj Damor

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How to solve Emails Are Going to Spam When Using SMTP Mail

5 min read
Why Your Emails Are Going to Spam When Using SMTP Mail || Manoj damor

Why Your Emails Are Going to Spam When Using SMTP Mail || Manoj damor

Email is a vital communication tool for businesses and individuals alike. However, one common issue many face is their emails being marked as spam. This can severely impact your communication effectiveness, lead to missed opportunities, and damage your reputation. Understanding why your emails are being flagged as spam when using Simple Mail Transfer Protocol (SMTP) is the first step towards improving your email deliverability. This blog post will explore the reasons behind this issue and provide actionable solutions.

1. Lack of Proper Authentication

Authentication is crucial in verifying that your emails come from a legitimate source. Without proper authentication, your emails are more likely to be marked as spam.

SPF (Sender Policy Framework): SPF records help identify which mail servers are permitted to send email on behalf of your domain. If you don’t have an SPF record, your emails might be flagged as suspicious.

DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to your emails, verifying that the message was not altered in transit and that it comes from your domain.

DMARC (Domain-based Message Authentication, Reporting, and Conformance): DMARC ties together SPF and DKIM, providing instructions to email servers on how to handle emails that fail authentication checks.

Solution: Ensure that your domain is configured with SPF, DKIM, and DMARC records. You can set these up in your domain’s DNS settings.

2. Poor IP Reputation

The reputation of your sending IP address significantly influences whether your emails end up in the inbox or the spam folder. If your IP address has been used for sending spam or malicious emails in the past, it will have a poor reputation.

Solution: Monitor your IP reputation using tools like Sender Score. If your IP reputation is low, consider using a different IP address or using a reputable email service provider with a good IP reputation.

3. High Bounce Rates

A high bounce rate indicates that a significant percentage of your emails are sent to invalid addresses. This can damage your sender reputation and increase the likelihood of your emails being marked as spam.

Solution: Regularly clean your email list to remove invalid or inactive addresses. Use email verification tools to ensure that your email list is up-to-date and contains valid addresses.

4. Content Issues

The content of your email plays a crucial role in determining whether it will be marked as spam. Several factors related to content can trigger spam filters:

  • Spammy Keywords: Words like “free,” “discount,” “winner,” and “urgent” can trigger spam filters.
  • Excessive Use of Images: Emails that contain more images than text can be flagged as spam.
  • Poor HTML Code: Broken or poorly formatted HTML can cause your email to be marked as spam.
  • Lack of Unsubscribe Link: Not including an easy way for recipients to unsubscribe can lead to spam complaints.

Solution: Create clean, well-formatted emails with a good balance of text and images. Avoid using spammy keywords and ensure that your HTML code is properly formatted. Always include an easy way for recipients to unsubscribe from your emails.

5. Misleading Subject Lines

Misleading or deceptive subject lines can cause recipients to mark your emails as spam, which can negatively impact your sender reputation.

Solution: Write clear and honest subject lines that accurately reflect the content of your email. Avoid using excessive punctuation, all caps, or misleading claims.

6. Sending Emails in Bulk Without Proper Permission

Sending unsolicited bulk emails, also known as spamming, is a sure way to get your emails marked as spam. Even if you’re sending legitimate emails, if recipients didn’t explicitly opt-in to receive them, your emails might be flagged as spam.

Solution: Use a double opt-in process to ensure that your recipients have explicitly agreed to receive emails from you. This involves sending a confirmation email to new subscribers, which they must acknowledge to complete their subscription.

7. Inconsistent Sending Patterns

Inconsistent or irregular sending patterns can raise red flags with email service providers (ESPs). Sending a large volume of emails at once after a period of inactivity can be seen as suspicious behavior.

Solution: Maintain a consistent sending schedule. If you need to increase your email volume, do so gradually to avoid triggering spam filters.

8. Lack of Engagement

Low engagement rates, such as low open rates and click-through rates, can signal to ESPs that your emails are not relevant or wanted by recipients, leading to higher chances of being marked as spam.

Solution: Segment your email list to send more targeted and relevant emails. Monitor engagement metrics and remove inactive subscribers regularly. Personalize your emails to make them more engaging and relevant to your audience.

9. Blacklisted Domains or IP Addresses

If your domain or IP address is on a blacklist, your emails are likely to be marked as spam. Blacklists are databases of IP addresses and domains known to send spam.

Solution: Regularly check if your domain or IP address is on any blacklists using tools like MXToolbox or MultiRBL. If you are blacklisted, follow the procedures provided by the blacklist to request removal and take steps to ensure your email practices comply with best practices.

10. Lack of Feedback Loop Monitoring

A feedback loop (FBL) is a service provided by some ESPs that notifies you when a recipient marks your email as spam. Not monitoring these complaints can lead to continued sending to uninterested recipients, harming your sender reputation.

Solution: Sign up for feedback loops with major ISPs and monitor spam complaints. Remove recipients who mark your emails as spam from your mailing list.

11. Inadequate Email Infrastructure

Your email infrastructure, including DNS settings, mail server configuration, and IP address management, plays a significant role in email deliverability. Inadequate infrastructure can lead to emails being marked as spam.

Solution: Ensure that your email infrastructure is properly configured. This includes setting up reverse DNS (PTR records), maintaining proper MX records, and using a dedicated IP address if necessary.


Emails being marked as spam can be a frustrating issue, but by understanding the common reasons behind it and implementing the solutions provided, you can significantly improve your email deliverability. Proper authentication, maintaining a good IP reputation, sending relevant and engaging content, and adhering to best practices are crucial steps in ensuring your emails reach the intended recipients’ inboxes.

By taking the time to audit your current email practices and making necessary adjustments, you can build a robust and effective email communication strategy that minimizes the risk of your emails being marked as spam. This not only enhances your communication efforts but also protects your sender reputation and fosters trust with your recipients.

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