Why are my standard emails still going to spam after fixing my IP address?
Michael Ko
Co-founder & CEO, Suped
Published 2 Jun 2025
Updated 16 Aug 2025
8 min read
It's a common scenario in email deliverability: you identify a core issue like an outdated IP address, fix it, and expect your emails to flow smoothly to the inbox. Then, weeks or months later, you find that your standard, one-to-one emails are still landing in spam folders. It's incredibly frustrating and can feel like you're back at square one.
The immediate thought is often, "Did my IP address fix not work?" While an IP address is a crucial component of your email infrastructure, it's far from the only factor influencing whether your messages reach their intended recipients. A single fix, even a significant one, doesn't always erase a history of deliverability problems.
This persistent spam folder issue points to deeper, often interconnected challenges beyond just your IP address. It suggests that while you've addressed one symptom, the underlying causes of poor deliverability might still be at play or have led to other lasting impacts. Understanding these additional factors is key to truly resolving the problem.
Understanding sender reputation and its lingering effects
Even after resolving an IP address issue, past sending behavior can leave a long shadow over your sender reputation. Internet Service Providers (ISPs) and mailbox providers like Gmail and Outlook maintain detailed sender histories, not just for your IP, but for your entire domain. If your domain previously engaged in practices that triggered spam filters, that historical data can continue to influence deliverability, even with a clean IP.
Your sender reputation is a holistic score. It factors in everything from bounce rates and spam complaint rates to user engagement (opens, clicks, replies). If these metrics were poor in the past, improving one aspect, like your IP address, won't instantly reset the overall perception. It takes consistent positive sending behavior over time to rebuild trust with mailbox providers. You can learn more about how long it takes to recover domain reputation from a bad or low state.
Mailbox providers use sophisticated algorithms to evaluate sender reputation. These systems are designed to protect users from unwanted email, and they err on the side of caution. If your domain has a history of problematic sending, even your personal, standard emails might be caught in broader filters designed to prevent spam. This is especially true if previous issues led to your domain being placed on a blacklist (or blocklist).
Technical foundations: Email authentication
Proper email authentication is non-negotiable for deliverability, regardless of your IP address. Protocols like SPF, DKIM, and DMARC verify that your emails are legitimately sent from your domain and haven't been tampered with. Even if your IP is clean, if these records are missing, misconfigured, or fail to align, mailbox providers will flag your emails as suspicious.
SPF (Sender Policy Framework) specifies which mail servers are authorized to send email on behalf of your domain. DKIM (DomainKeys Identified Mail) adds a digital signature to your outgoing emails, allowing recipient servers to verify that the message wasn't altered in transit. DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM, providing instructions to recipient servers on how to handle emails that fail authentication and offering reporting capabilities.
Many senders think these are only for bulk mail, but they are critical for all email. Even standard, personal emails benefit from and often require correct authentication to reach the inbox. Mailbox providers are increasingly strict, and a lack of proper authentication (even with a good IP) can easily lead to emails being sent to spam. If your emails are landing in spam despite passing SPF, DKIM, and DMARC, other factors are likely at play.
Broken authentication
Issue: SPF record is missing or includes incorrect IP addresses. DKIM signatures are invalid or not present. DMARC policy is set to quarantine or reject but alignment fails.
Impact: Mailbox providers view emails as unverified or spoofed, even from a clean IP. This significantly increases the likelihood of landing in the spam folder.
Consequences: Rejection of emails, routing to spam, and rapid degradation of your domain's reputation.
Proper authentication
Solution: Ensure all sending IPs are in SPF. Implement a valid DKIM record. Set up a DMARC record and monitor reports to ensure SPF and DKIM alignment.
Benefit: Mailbox providers trust your email's origin. This is a fundamental step for good deliverability and is essential for avoiding the spam folder.
Even with a healthy IP and perfect authentication, the content of your emails can trigger spam filters. Certain words, phrases, formatting, or even the ratio of images to text can be red flags. While standard, one-to-one emails are less prone to this than bulk marketing emails, it's still a possibility. This is especially true if previous sending habits from your domain involved overly promotional or questionable content.
Engagement is another major factor. Mailbox providers track how recipients interact with your emails. If your emails are frequently deleted without being opened, marked as spam, or simply ignored, this signals to providers that your emails aren't desired. This negative engagement data, tied to your domain, can lead to future messages being sent to the spam folder, regardless of your IP.
Poor list hygiene can also contribute. Sending to invalid or inactive email addresses can lead to high bounce rates or hitting spam traps, both of which severely damage your sender reputation. While this is less likely for standard one-to-one emails to known contacts, it's worth considering if your broader sending practices include any form of bulk messaging to unverified lists. Learn more about why your emails are going to spam.
Example: Common spam content triggers
Excessive capitalization or exclamation points: "FREE MONEY NOW!!!"
Spam trigger words: "Limited time offer," "Guaranteed income."
Broken HTML or poor formatting: Overly complex or poorly coded email templates.
Image-only emails: Lack of text content to analyze, looks suspicious.
Suspicious links: Links to domains with poor reputation or shortened URLs without context.
Hidden pitfalls and ongoing monitoring
Even if your current IP is clean, your previous IP (or even your domain itself) might be listed on a blocklist (or blacklist). These lists are used by mailbox providers to filter out unwanted email. Being listed, even temporarily, can severely impact deliverability. While fixing your IP is a step, it doesn't automatically remove you from these lists. Each blocklist has its own delisting process, and some require a period of good behavior before removal.
Another often-overlooked aspect is reverse DNS (rDNS). An rDNS record ensures that your IP address points back to your domain name. This creates a trust signal for recipient servers. If your IP address was recently changed, ensure that the new IP has a correctly configured rDNS record. A missing or incorrect rDNS mapping can make your email server look unconfigured or suspicious, causing even standard emails to be flagged.
Recipient feedback is a powerful signal. If recipients mark your emails as spam, even a small number, it negatively impacts your reputation. This is especially damaging for transactional or one-to-one emails where the expectation of relevance is high. Implementing an easy unsubscribe option for all applicable emails and monitoring complaint rates are essential, even for standard messages if they are part of a larger communication stream.
Finally, remember that the email landscape is constantly evolving. Mailbox providers frequently update their filtering algorithms. What worked last month might not work today. This underscores the need for continuous monitoring of your deliverability metrics, including spam rates, bounce rates, and authentication results, to identify and address issues proactively. Discover more about why your emails are going to spam and how to fix it.
Essential technical checks
Check all IP addresses: Verify all current and previous sending IPs are not on any major blacklists. Use a blocklist checker to monitor regularly.
Verify rDNS records: Ensure your new IP has a valid rDNS entry that points to your sending domain. This is often configured by your hosting provider.
Monitor spam trap hits: Hitting spam traps indicates a problematic list. Review your list acquisition and hygiene processes.
Review email content: Even for standard emails, check for excessive links, spammy phrases, or unusual formatting.
Views from the trenches
Best practices
Always maintain robust SPF, DKIM, and DMARC records to authenticate your email sender.
Regularly monitor your domain and IP reputation using postmaster tools and blocklist checkers.
Segment your email sending by type (transactional, marketing, one-to-one) and use appropriate sending infrastructure.
Implement feedback loops with major mailbox providers to quickly address user complaints.
Practice continuous list hygiene to remove inactive or invalid email addresses and prevent spam trap hits.
Common pitfalls
Assuming an IP fix is a complete solution, neglecting underlying domain reputation issues.
Not configuring reverse DNS for new or updated IP addresses.
Ignoring subtle content triggers or formatting issues in standard emails.
Failing to monitor DMARC reports for authentication failures or misconfigurations.
Using the same sending domain or IP for vastly different email types (e.g., outreach and transactional).
Expert tips
If you're using a third-party email service, ensure their SPF and DKIM setup is correctly configured for your domain.
Check for any
link missing from this list
or
broken DKIM signatures
Expert view
Expert from Email Geeks says the first thing to check should be the email authentication protocols like DMARC and SPF.
July 26, 2021 - Email Geeks
Marketer view
Marketer from Email Geeks says you should look into what else your client is doing that might make their business-to-business mail appear suspicious, such as using G-Suite for outreach-style emails which could harm their reputation.
July 26, 2021 - Email Geeks
A holistic approach to deliverability
While fixing your IP address is a crucial step toward better email deliverability, it's rarely a magic bullet. The email ecosystem is complex, and many factors contribute to whether your emails land in the inbox or the spam folder. From lingering domain reputation issues and authentication gaps to content quality, recipient engagement, and even obscure blocklist entries (or blacklists), each element plays a significant role.
Addressing these multifaceted challenges requires a holistic approach. It's not about making a single fix but implementing consistent best practices across your entire email program. This means regular monitoring, diligent adherence to authentication standards, careful content creation, and proactive list management.
By understanding and optimizing all aspects of your email sending, you can move beyond frustrating spam folder issues and ensure your standard, important communications consistently reach their intended recipients. It's a continuous journey, but one that yields significant returns in trust and successful communication.
Gmail and 
Outlook maintain detailed sender histories, not just for your IP, but for your entire domain. If your domain previously engaged in practices that triggered spam filters, that historical data can continue to influence deliverability, even with a clean IP.
