Is Domain Reputation More Important Than IP Reputation for Email Deliverability?
Michael Ko
Co-founder & CEO, Suped
Published 21 May 2025
Updated 18 Aug 2025
7 min read
For many years, discussions about email deliverability predominantly revolved around IP (Internet Protocol) reputation. It was the primary metric by which Internet Service Providers (ISPs) judged the trustworthiness of incoming email. If your IP address had a good track record, your emails were likely to land in the inbox.
However, the email landscape has evolved significantly. With the proliferation of cloud-based sending platforms and shared IP addresses, ISPs have shifted their focus to more granular indicators of sender trustworthiness. This shift has brought domain reputation to the forefront of deliverability concerns, prompting a critical question: Is domain reputation now more important than IP reputation?
The truth is nuanced. Both IP and domain reputation play vital roles, but their relative importance has changed. Understanding this dynamic is crucial for ensuring your emails consistently reach the inbox.
The foundation of trust: IP reputation
Your IP reputation is a score assigned to the specific server or set of servers from which your emails originate. This score reflects the historical sending behavior from that IP address. Factors like the volume of spam sent, bounce rates, and whether the IP address is listed on any blocklists (or blacklists) heavily influence this reputation.
A good IP reputation signals to receiving mail servers that emails from this source are generally legitimate and trustworthy. Conversely, a poor IP reputation can lead to emails being immediately rejected or sent straight to the spam folder, regardless of the content or the sender's domain. In some cases, a very low IP reputation can act as an initial filter, preventing mailbox providers from even evaluating your domain reputation.
While IP reputation was once the dominant factor, its impact can vary, particularly for senders using shared IP addresses. If you're using a shared IP, your reputation is tied to the sending practices of all other users on that IP, making it harder to control. Even with shared IPs, maintaining a good IP reputation remains fundamental to deliverability. You can learn more about how IP reputation plays a crucial role in determining whether your emails land in inboxes or get flagged as spam in this guide to IP reputation.
The impact of a poor IP reputation
A low or negative IP reputation can have immediate and severe consequences for your email deliverability. Mailbox providers might instantly reject your messages, leading to high bounce rates and failure to reach your recipients.
This can happen even if your domain has a strong reputation, because the IP acts as a preliminary gatekeeper. Monitoring for IP blocklisting (or blacklisting) is therefore essential.
After establishing your IP reputation, there needs to be sufficient content between rich components to ensure optimal readability and user experience.
The email deliverability landscape constantly changes, with new factors gaining prominence. Keeping abreast of these shifts is key to maintaining high inbox placement rates.
Domain reputation's growing influence
Domain reputation refers to the trustworthiness associated with your sending domain (the part after the '@' symbol in an email address). This reputation is built over time based on various factors, including the quality of content, subscriber engagement, complaint rates, and the proper implementation of email authentication protocols like SPF, DKIM, and DMARC. It's a more permanent and brand-centric measure compared to IP reputation.
Modern email filtering systems, particularly those used by major ISPs like Gmail and Yahoo, increasingly prioritize domain reputation. They view your domain as a direct representation of your brand's trustworthiness, making it a crucial factor for long-term sender assessment. This shift reflects a move towards evaluating the sender's identity rather than just the sending infrastructure.
The consistent engagement of your recipients with your emails (opens, clicks, replies) and low complaint rates significantly bolster your domain reputation. Conversely, high spam complaint rates or frequent bounces can quickly damage it, leading to emails being directed to the spam folder. Understanding the nuances of how domain reputation affects deliverability is paramount in today's email environment.
IP reputation factors
Volume consistency: Sudden spikes or drops in sending volume can negatively impact. Warming up your IP is critical.
Spam complaints: High rates indicate unwanted mail and quickly lower the score.
Bounce rates: Hard bounces (non-existent addresses) are particularly damaging.
Blocklists: Being listed on a major blocklist (or blacklist) can lead to widespread delivery issues.
Domain reputation factors
Engagement metrics: Open rates, click-through rates, and read times signal positive user interaction.
Spam complaints: Similar to IP, high complaint rates negatively affect your domain's standing.
Email authentication: Proper configuration of SPF, DKIM, and DMARC is critical for domain trust.
Content quality: Irrelevant or spammy content harms your domain's perceived quality.
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The evolution of email security measures means that a holistic approach to sender reputation is increasingly necessary. No single factor can guarantee inbox placement.
How IP and domain reputation interact
The relationship between IP and domain reputation is not one of either/or, but rather a synergistic one. Think of IP reputation as the reputation of the physical mail truck delivering your letter, and domain reputation as the reputation of your brand on the letterhead. Both need to be trustworthy for your mail to reach its destination.
If your IP reputation is severely compromised, emails may be rejected outright, preventing mailbox providers from even assessing your domain's credibility. However, once your emails are accepted for initial delivery, domain reputation becomes the dominant factor in determining inbox placement (in the primary inbox, promotions tab, or spam folder).
Leading ISPs, such as Gmail and Yahoo, increasingly prioritize domain-based filtering due to the rise of shared IP addresses and advanced spam detection techniques. They can differentiate between many domains sending from the same IP, giving more weight to the specific domain's history and authentication. This is why Gmail's prioritization of domain reputation has become a common discussion point.
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This holistic approach by mailbox providers means that even if your IP is shared, your individual domain's behavior can significantly influence your deliverability outcomes. Focusing solely on one reputation type while neglecting the other is a recipe for deliverability issues.
Strategies for enhancing your sender reputation
To ensure strong deliverability, you need to proactively manage both your IP and domain reputations. This involves implementing best practices across your email program. The primary goal should always be to send desired, relevant mail to engaged recipients.
For your domain reputation, proper email authentication is non-negotiable. Ensure your SPF, DKIM, and DMARC records are correctly configured and aligned. This proves to ISPs that you are the legitimate sender of emails from your domain, significantly boosting your domain's credibility. For example, Klaviyo users often resolve deliverability issues by ensuring proper DKIM signing with their client's domain.
Regularly monitor your IP and domain blocklist (blacklist) status. Addressing any listings promptly can prevent long-term damage. Also, segment your audience and tailor your content to maximize engagement and minimize complaints. By actively managing these aspects, you can significantly improve overall email deliverability rates.
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Aspect
IP reputation improvement
Domain reputation improvement
List hygiene
Regularly remove invalid or inactive addresses to reduce bounce rates and avoid spam traps.
Maintain an engaged subscriber list to minimize complaints and maximize positive engagement metrics.
Sending volume
Gradually increase volume (IP warming) when using new IPs to build a positive sending history.
Ensure consistent sending patterns and avoid sending large, sporadic campaigns that can appear suspicious.
Authentication
While not directly tied to IP, proper SPF records help validate the sending IP.
It is crucial to remember that both IP and domain reputation are important for email deliverability. While domain reputation has gained significant ground as the primary long-term identifier of trust for mailbox providers, IP reputation still serves as a critical initial filter. A bad IP reputation can prevent your emails from ever reaching the point where domain reputation is assessed. To truly succeed in email marketing and ensure your messages consistently reach their intended recipients, a balanced and comprehensive approach that addresses both aspects is indispensable. Neglecting either one can lead to emails going to spam.
Views from the trenches
Best practices
Implement strong email authentication (SPF, DKIM, DMARC) for all sending domains.
Consistently monitor both IP and domain blocklists (blacklists) to quickly address any issues.
Focus on engagement: send relevant content to an interested audience to improve domain metrics.
Warm up new IPs and domains gradually to build a positive sending history with ISPs.
Common pitfalls
Ignoring IP reputation, especially on shared IPs, can lead to immediate rejections.
Neglecting email authentication leaves your domain vulnerable to spoofing and reputation damage.
Sending to unengaged lists, resulting in high spam complaints and low engagement.
Sudden, unannounced spikes in email volume, which can trigger spam filters.
Expert tips
Domain reputation has been important for about a decade but has gained increased prominence recently.
For optimal deliverability, you cannot ignore either domain or IP reputation, as they are both crucial.
Ensure DKIM signing is configured for your actual domain, not just the sending platform's default domain.
Microsoft remains a notable mailbox provider where IP reputation still significantly impacts deliverability.
Marketer view
Marketer from Email Geeks says that while everything in email deliverability is important, domain reputation has recently gained much more awareness and prominence.
2024-03-01 - Email Geeks
Expert view
Expert from Email Geeks says that domain reputation has been relevant for about ten years, but its influence has grown considerably in recent years due to new ways it is being leveraged.
