How does domain reputation affect email deliverability compared to IP reputation?
Michael Ko
Co-founder & CEO, Suped
Published 11 Jun 2025
Updated 16 Aug 2025
8 min read
When we talk about email deliverability, the concepts of IP reputation and domain reputation often come up together. While both are critical for ensuring your emails reach the inbox, they play distinct, though sometimes overlapping, roles. Historically, IP reputation was often seen as the primary gatekeeper, but the landscape has evolved significantly.
Many email senders, especially those utilizing shared IP addresses, frequently wonder if a strong IP reputation can counteract a poor domain reputation, or vice versa. The answer is nuanced, but increasingly, domain reputation holds the ultimate sway over whether your messages land in the primary inbox or the spam folder.
I've observed that modern mailbox providers have refined their filtering algorithms to prioritize the long-term trustworthiness associated with a sender's domain. This shift means that understanding both types of reputation and how they interact is more crucial than ever for maintaining optimal email deliverability.
Understanding IP reputation
IP reputation refers to the trustworthiness associated with the specific server, identified by its IP address, from which your emails are sent. This reputation is built over time based on the sending behavior originating from that IP address. Factors like the volume of emails sent, consistency of sending, and crucially, the number of spam complaints or bounces generated from that IP directly influence its standing.
A positive IP reputation is vital for the initial acceptance of your emails by receiving mail servers. If an IP address has a history of sending spam or malicious content, it may be placed on a blocklist (or blacklist). When an IP is on a blocklist, incoming mail servers may outright reject emails from it, or shunt them directly to the junk folder without further assessment. This is why an IP blocklist entry can severely impact your ability to deliver emails.
However, IP reputation is not entirely portable. If you switch email service providers (ESPs) or move to a new IP address, you start with a fresh or shared IP reputation. This often necessitates an IP warming process to gradually build up trust with mailbox providers. On a shared IP, your reputation is also influenced by the sending habits of other users on that same IP, which can be a double-edged sword.
The growing importance of domain reputation
Domain reputation is a measure of the trustworthiness of your sending domain (e.g., example.com) itself. Unlike IP reputation, which is tied to a specific server, domain reputation is associated with your brand and follows you regardless of the IP address you use to send emails. This makes it a more persistent and valuable asset for long-term email marketing efforts.
Your domain's reputation is influenced by a comprehensive set of factors, including recipient engagement metrics such as opens, clicks, and replies. Conversely, negative interactions like unsubscribes, deletions without opening, and critically, spam complaints and hitting spam traps, severely degrade your domain's standing. Proper email authentication, including SPF, DKIM, and DMARC, also significantly contributes to building and maintaining a good domain reputation by verifying your identity as a sender.
The portability of domain reputation is a key differentiator. If you decide to change ESPs, or if your current ESP migrates your account to new IPs, your established domain reputation largely carries over. This means that a domain with a consistent history of good sending practices will likely continue to experience strong deliverability, even with changes to its underlying IP infrastructure.
Mailbox providers such as Google and Yahoo increasingly prioritize domain reputation in their filtering decisions. They view the domain as the consistent identifier of the sender, and its long-term track record of sending desired mail is a stronger signal than the ephemeral nature of IP addresses.
The interplay between IP and domain reputation
While IP reputation is crucial for the initial acceptance of your emails by recipient servers, domain reputation plays a more significant role in determining where those emails ultimately land—in the inbox or the spam folder. I often think of IP reputation as getting your foot in the door, while domain reputation dictates what happens once you're inside.
Consider a scenario where you're sending from a shared IP with an excellent reputation. If your domain has a history of high complaint rates or low engagement, your emails can still end up in spam, overriding the positive influence of the IP. This is because ISPs like Mailgun and Twilio increasingly view the domain as the true identity of the sender. For a deeper dive into the distinctions, this article from Twilio on IP vs. Domain Reputation offers valuable insights.
This doesn't mean IP reputation is irrelevant. If your IP address is on a major blocklist, your emails won't even have a chance for their domain reputation to be assessed. The IP serves as the first line of defense, ensuring your mail is initially accepted. But once past that hurdle, the domain's history and practices heavily influence the final inbox placement decision. This is especially true with services that use advanced filtering based on sender behavior.
IP reputation (the server)
Focus: Measures the trustworthiness of the specific IP address sending the email.
Primary role: Enables initial acceptance by the receiving mail server. A poor IP can lead to immediate rejections or blocklisting.
Volatility: Can be affected by other senders on a shared IP, making it less stable.
Management: Often managed by your ESP, especially on shared IPs.
Domain reputation (your brand)
Focus: Measures the trustworthiness of your domain name across all sending activities.
Primary role: Drives inbox vs. spam folder placement. A poor domain can lead to emails being filtered despite a good IP.
Portability: Stays with your domain even if you change ESPs or IP addresses.
Management: Largely controlled by your email sending practices and content.
Building and maintaining reputation
To build and maintain a robust sender reputation, you need to implement consistent best practices that positively influence both your IP and domain standing. First and foremost, focus on list hygiene. Regularly cleaning your email list to remove invalid, inactive, or unengaged addresses reduces bounces and improves engagement metrics, which are crucial for both reputation types.
Engagement is king in the eyes of mailbox providers. High open rates, click-through rates, and low unsubscribe rates signal that your content is valued by recipients. Conversely, if recipients frequently delete your emails without opening them, or worse, mark them as spam, it will significantly damage your domain reputation.
Email authentication protocols like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) are foundational. These mechanisms prove that your emails are legitimate and originate from your domain, preventing spoofing and building trust. A properly configured DMARC policy is particularly important for gaining major providers' trust.
Best practices for reputation management
Maintain clean lists: Remove inactive subscribers and invalid email addresses regularly to reduce bounces and improve engagement metrics.
Monitor engagement: Track opens, clicks, and unsubscribes. High engagement signals positive reputation.
Implement authentication: Properly set up SPF, DKIM, and DMARC records to verify your sending identity and prevent spoofing.
Segment your audience: Send relevant content to specific groups to boost engagement and reduce complaints.
Monitor blocklists: Regularly check if your IP or domain is listed on any email blacklists (or blocklists).
Views from the trenches
Best practices
Actively manage unengaged subscribers by segmenting them and trying re-engagement campaigns.
Always use a clear unsubscribe link and honor opt-out requests promptly to reduce spam complaints.
Ensure all email authentication records (SPF, DKIM, DMARC) are correctly configured and monitored.
Regularly monitor your domain and IP reputation using reputable postmaster tools.
Common pitfalls
Ignoring low engagement metrics, which can signal declining interest to mailbox providers.
Not removing hard bounces from your lists, as they significantly harm both IP and domain reputation.
Relying solely on IP reputation without understanding the increasing importance of domain reputation.
Sending emails to purchased or old lists that contain spam traps.
Expert tips
Even with a shared IP, your domain reputation can independently lead to spam folder placement.
Mailbox providers increasingly prioritize domain reputation for inbox versus spam folder decisions.
If emails are accepted but land in spam, the issue is often with domain reputation, not the IP.
All elements in an email, including tracking domains, contribute to the overall sender score.
Marketer view
Marketer from Email Geeks says: It is absolutely possible for emails to go to spam due to poor domain reputation, even on a shared IP with a good reputation.
2022-05-05 - Email Geeks
Expert view
Expert from Email Geeks says: Domain reputation, not IP address, is what determines if an email goes to the inbox or the spam folder once the mail has been accepted by the MX.
2022-05-05 - Email Geeks
The path to inbox success
The distinction between IP and domain reputation is more critical than ever for email deliverability. While both contribute to your overall sender reputation, domain reputation has increasingly become the dominant factor for determining inbox placement. An excellent IP will get your emails through the initial gate, but your domain's consistent sending practices and recipient interactions ultimately decide their fate.
For senders on shared IPs, understanding this distinction is particularly important. A good shared IP helps, but a poor domain reputation can still lead to emails landing in spam. It's crucial to proactively manage your domain's health through consistent positive sending behaviors, strong email authentication, and diligent monitoring.
By prioritizing efforts to nurture your domain's reputation, you invest in a more resilient and portable asset that will serve your email program well into the future, regardless of changes to your sending infrastructure.
Google and 
Yahoo increasingly prioritize domain reputation in their filtering decisions. They view the domain as the consistent identifier of the sender, and its long-term track record of sending desired mail is a stronger signal than the ephemeral nature of IP addresses.
Mailgun and 
Twilio increasingly view the domain as the true identity of the sender. For a deeper dive into the distinctions, this article from Twilio on IP vs. Domain Reputation offers valuable insights.
