What are effective strategies to avoid spam traps and improve email deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 26 Apr 2025
Updated 19 Aug 2025
7 min read
Email deliverability is a critical aspect of any successful email marketing or communication strategy. It's not just about sending emails, it's about ensuring they land in the recipient's inbox, not their spam folder. A major hurdle in achieving high deliverability is avoiding spam traps. These are decoy email addresses set up by Internet Service Providers (ISPs) and anti-spam organizations to identify and block (or blacklist) senders who engage in questionable email practices, such as sending to outdated, purchased, or scraped lists.
Hitting a spam trap, even once, can severely damage your sender reputation and lead to your emails being consistently diverted to spam or outright rejected. This can have a devastating impact on your campaign performance, customer engagement, and ultimately, your bottom line. I've learned that preventing spam trap hits and maintaining a stellar sender reputation is paramount to email success. It requires a proactive approach to list management, authentication, and content creation.
In this guide, I'll share effective strategies to navigate the complexities of email deliverability, minimize your exposure to spam traps (also known as blocklist traps), and ensure your legitimate messages reach their intended recipients.
Building and maintaining a high-quality email list
The foundation of good email deliverability is a clean, engaged email list. The origin of your email addresses is often where problems begin. If you're acquiring addresses through methods other than direct, explicit opt-in, you're exposing yourself to significant risk.
I’ve seen firsthand how quickly a list can become tainted if proper acquisition methods aren't in place. If users can simply enter an email address to gain access to content without any verification, many will provide fake or unused addresses. These can often be spam traps. This scenario is particularly dangerous and almost guarantees a list filled with issues.
Implement double opt-in
Double opt-in is a crucial best practice for list building. After a user signs up, a confirmation email is sent to their inbox, requiring them to click a link to confirm their subscription. This verifies that the email address is valid and that the subscriber genuinely wants to receive your emails. This simple step can drastically reduce the number of invalid or fake addresses on your list, thereby minimizing your exposure to spam traps. It also indicates a higher level of engagement from your subscribers.
Beyond initial acquisition, continuous list hygiene is vital. Regularly removing inactive subscribers is a powerful strategy to avoid hitting recycled spam traps (email addresses that were once valid but have since been abandoned and repurposed by ISPs as traps). An email address that never opens your mail, or has been inactive for a significant period, might be a signal to machine learning filters that your mail isn't relevant. Sending to these addresses can negatively impact your sender reputation, even if they aren't explicit spam traps.
Understanding sender reputation and email authentication
Your sender reputation is a score assigned by ISPs based on your sending practices and subscriber engagement. A good reputation tells ISPs that you are a legitimate sender, increasing the likelihood of your emails reaching the inbox. Conversely, a poor reputation can lead to your emails being flagged as spam or outright blocked. This is why it's crucial to consistently improve your email reputation.
Email authentication protocols like SPF, DKIM, and DMARC are fundamental to building and maintaining a strong sender reputation. These protocols verify that an email truly originates from the domain it claims to be from, preventing spoofing and phishing attempts. Implementing these correctly signals trustworthiness to ISPs.
Monitoring your DMARC reports provides invaluable insights into your email authentication status and potential issues. For instance, Gmail, while not heavily reliant on spam traps, places significant emphasis on engagement and authentication. If Gmail users are not interacting with your messages, it hurts your overall delivery, regardless of spam trap hits. You can learn more about this in this article on Gmail's bulk folder behavior.
Strong authentication
SPF: Authorizes mail servers to send on behalf of your domain.
DKIM: Digitally signs your emails, verifying content integrity and sender identity.
DMARC: Builds on SPF and DKIM, providing instructions to receiving servers on how to handle unauthenticated mail and enabling reporting.
Weak authentication
Missing SPF/DKIM: Increases spam filter suspicion and can lead to emails being rejected.
No DMARC: Leaves your domain vulnerable to spoofing and phishing, harming your reputation.
Misconfigured records: Can result in legitimate emails failing authentication and being marked as spam.
If you are on a shared IP address, deliverability issues can sometimes arise due to the sending practices of others on the same IP. However, many major mailbox providers, like Google, are very good at separating mail based on sender domain reputation, even on shared IPs. This means your individual domain's reputation and adherence to best practices often matter more than the shared IP itself. Monitoring your domain reputation through tools like Google Postmaster Tools is essential.
Optimizing email content and sending behavior
The content of your emails plays a significant role in deliverability. Spam filters analyze various elements, including subject lines, body text, links, and formatting, for indicators of spam. Avoiding 'spammy' content is crucial. This includes excessive capitalization, exclamation marks, suspicious phrases (e.g., 'free money', 'guaranteed'), and too many links or attachments. Using link shorteners can also trigger spam filters, as they are often used in malicious emails.
Beyond content, your sending behavior matters. Inconsistent sending patterns can raise red flags with ISPs. For example, if you suddenly send a massive volume of emails after a long period of inactivity, it can look suspicious. Gradual IP warming for new IPs or domains helps build a positive sending history. Also, ensure your emails render correctly across various email clients and include both HTML and plain-text versions.
Best practice
Pitfall to avoid
Clear, concise subject lines that accurately reflect content
Using deceptive or overly promotional subject lines
Relevant and engaging content tailored to subscriber interests
Sending generic, irrelevant, or overly sales-oriented messages
Maintaining a consistent sending frequency and volume
Erratic sending patterns or sudden spikes in volume
Ensuring proper HTML and plain text email formatting
Poorly coded HTML, broken layouts, or image-only emails
Including a clear and easy-to-find unsubscribe link
Hiding or omitting unsubscribe options, leading to complaints
Engagement is king. ISPs closely monitor how subscribers interact with your emails. Opens, clicks, and replies are positive signals, while low engagement, deletions without opening, and marking as spam are negative. Regularly segment your list and prioritize sending to your most engaged subscribers. This can help improve your overall sender reputation and prevent your emails from being directed to the spam folder. If emails are consistently going to spam, it's critical to diagnose and fix the issue.
Views from the trenches
Best practices
Actively handle bounces and clean inactive addresses regularly, especially those over 12-18 months old.
Verify new email addresses at signup to ensure they are real and belong to the user.
Segment your audience and prioritize sending to recently engaged subscribers to boost reputation.
Ensure your email authentication (SPF, DKIM, DMARC) is correctly configured and monitored.
Maintain consistent sending volumes and frequencies to avoid suspicious activity flags.
Common pitfalls
Forcing email submission for content access without verification leads to high spam trap hits.
Ignoring inactive subscribers, as this can signal low relevance to machine learning filters.
Blaming shared IP addresses too quickly; focus on your own sending practices first.
Not removing addresses that deliver to spam, which negatively impacts overall reputation.
Sending a large volume of emails at once after a long period of inactivity.
Expert tips
Monitor Google Postmaster Tools for Gmail-specific insights on your reputation.
Consider a reset or address confirmation for users who return after long periods of inactivity.
Review your sunset flow for inactive users, especially if it involves large, sudden sends.
Understand that some mailbox providers prioritize engagement over spam trap hits.
Continuously adapt your strategies based on ISP feedback and deliverability data.
Marketer view
Marketer from Email Geeks says: The problem usually starts with how the email addresses were acquired. Always look at the source first.
2019-10-28 - Email Geeks
Marketer view
Marketer from Email Geeks says: If users only need to enter an address to view content without verification, they are likely to provide fake or unused addresses, which quickly leads to a spam trap filled list.
2019-10-28 - Email Geeks
Enhancing your email program for better deliverability
Avoiding spam traps and improving email deliverability is an ongoing process that requires diligent attention to your email program's every facet. It's not a one-time fix but a continuous commitment to best practices. From the moment you acquire an email address to every message you send, your actions contribute to your sender reputation and inbox placement rates.
By prioritizing permission-based list building, implementing robust authentication, maintaining strict list hygiene, and optimizing your content and sending behavior, you can significantly reduce your risk of hitting spam traps. This also ensures your messages bypass spam filters and consistently reach the inboxes of your engaged audience, fostering better relationships and driving superior results from your email campaigns. Remember that continuous monitoring and adaptation are key to navigating the ever-evolving landscape of email deliverability. For more in-depth information, consider exploring our guide on email deliverability issues.
Gmail, while not heavily reliant on spam traps, places significant emphasis on engagement and authentication. If 
Google, are very good at separating mail based on sender domain reputation, even on shared IPs. This means your individual domain's reputation and adherence to best practices often matter more than the shared IP itself. Monitoring your domain reputation through tools like 
