What is the difference between IP and domain reputation in email deliverability?
Matthew Whittaker
Co-founder & CTO, Suped
Published 18 May 2025
Updated 19 Aug 2025
8 min read
When it comes to email deliverability, understanding the difference between IP reputation and domain reputation is crucial. These two distinct factors play pivotal roles in determining whether your emails land in the inbox or end up in the spam folder. While often discussed together, they refer to different aspects of your email sending infrastructure and behavior.
In the early days of email, IP reputation was almost exclusively what mattered. Internet Service Providers (ISPs) primarily focused on the sending IP address to assess trustworthiness. However, as the email landscape evolved and spam tactics became more sophisticated, a more granular and persistent identifier was needed. This led to the rise of domain reputation as a critical assessment.
Both IP and domain reputation are components of your overall sender reputation, which mail servers use to decide if they can trust emails from a particular source. A good sender reputation is the cornerstone of successful email marketing and communication. Without it, even perfectly crafted emails can fail to reach their intended recipients.
What is IP reputation?
IP reputation refers to the trustworthiness associated with the specific Internet Protocol address (or range of addresses) from which your emails are sent. This reputation is primarily built upon the sending behavior originating from that IP address. It's essentially a score assigned by receiving mail servers based on the historical performance of emails sent from that particular IP.
Factors influencing IP reputation include the volume and frequency of emails sent, bounce rates, spam complaint rates, whether the IP is listed on any email blocklists or blacklists, and recipient engagement (opens, clicks). If an IP consistently sends out high-quality, relevant emails that recipients engage with, it's more likely to enjoy a positive reputation. Conversely, an IP associated with spamming behavior will quickly gain a negative reputation, leading to emails being blocked or sent to spam.
IP reputation can be thought of as the initial gatekeeper. It determines how quickly and readily a recipient's mail server will accept your emails for further processing. For example, if your IP has a poor reputation, a mail server might implement greylisting or outright reject your connection before even evaluating your domain. This can be particularly impactful on B2B email deliverability.
IP reputation factors
Volume: Consistency of sending volume and adherence to typical patterns. Sudden spikes can be flagged as suspicious.
Complaints: Low rates of users marking emails as spam. High complaint rates are a major red flag for any IP address.
Bounces: Managing and cleaning your list to minimize hard bounces. High bounce rates signal a poorly maintained list, impacting sender reputation with ISPs.
Domain reputation focuses on the trustworthiness of your sending domain, which is the part of your email address after the '@' symbol (e.g., yourcompany.com). This reputation is tied to your brand and email identity, rather than just the server sending the mail. Because it's tied to your brand, domain reputation is more enduring and portable, meaning it follows you even if you change email service providers (ESPs) or IP addresses. It cannot be easily reset.
Domain reputation is influenced by factors similar to IP reputation, but with a stronger emphasis on overall sender practices and recipient engagement related to the domain itself. This includes subscriber engagement, spam complaint rates, spam trap hits, whether your domain is spoofed, and the proper configuration of email authentication protocols like SPF, DKIM, and DMARC. Domain reputation also considers how your emails are handled after acceptance, such as being placed in the inbox versus the spam folder.
While IP reputation gets your foot in the door, domain reputation determines where your emails ultimately land. A strong domain reputation signals to ISPs like Gmail and Yahoo that your brand is legitimate and sends desired communications. Many major providers today place significant weight on domain reputation. You can often see a summary of your domain's reputation with tools like Google Postmaster Tools, which provides insights into your sending reputation metrics.
The interaction between IP and domain reputation
While distinct, IP and domain reputation are not entirely independent. They work in tandem to form your overall sender reputation. IP reputation is the connection and first part of the SMTP transaction; it gets you in the door. Once the message is accepted, then domain reputation takes over. That’s the primary driver of inbox versus bulk delivery.
If you are on a shared IP address, your IP reputation is influenced by the sending behavior of everyone else using that same IP. This means that a good domain reputation might be undermined by a poor shared IP reputation, and vice-versa. However, many major mailbox providers (MBPs) today, particularly consumer-facing ones, tend to prioritize domain reputation more heavily. This is because domain reputation is more precise and tied directly to the sender's brand identity, offering a more stable indicator of sending history than an IP address, which can change or be shared among many senders. Reputation is in the eye of the beholder.
For instance, if your domain has a strong reputation but you're sending from an IP with a poor one, your emails might still experience deliverability issues, especially with providers that weigh IP reputation heavily (like some older or B2B mail servers). Conversely, a strong IP reputation can't entirely compensate for a domain that consistently sends unwanted emails. Ultimately, both must be maintained for optimal inbox placement.
IP reputation
Scope: Linked to the physical server or sending service.
Portability: Not portable. Changes if you switch IPs or ESPs. Can be shared.
Impact: Affects the initial connection and acceptance rate by recipient servers.
To ensure high email deliverability, you must actively manage both your IP and domain reputations. Neglecting either can lead to your emails being rejected or diverted to spam folders. This is why tools that provide a comprehensive email deliverability test are so valuable.
Maintaining a healthy IP reputation involves practices like consistent sending volumes, avoiding spam traps, and promptly removing invalid email addresses from your lists to minimize hard bounces. If you're using a dedicated IP, you have full control over its reputation. With shared IPs, you're reliant on the overall sending quality of others using the same IP, making domain reputation even more critical.
For domain reputation, implementing email authentication standards like SPF, DKIM, and DMARC is non-negotiable. These protocols prove that your emails are legitimately from your domain and haven't been tampered with. Beyond technical configurations, maintaining a clean and engaged subscriber list is paramount. High user engagement (opens, clicks, replies) and low spam complaint rates significantly boost your domain's standing with ISPs. Conversely, excessive spam reports can quickly tank your domain reputation, regardless of your IP.
Regularly monitoring both your IP and domain reputation is essential for proactive deliverability management. Leveraging Google Postmaster Tools can provide valuable insights into your domain's performance with Google properties, helping you identify and address issues before they significantly impact your campaigns. Maintaining both positive IP and domain reputations is the key to consistent inbox delivery.
Views from the trenches
Best practices
Maintain consistent sending volumes and avoid sudden spikes to protect IP reputation.
Implement and monitor SPF, DKIM, and DMARC records for robust domain authentication.
Prioritize email list hygiene, regularly removing inactive or bounced addresses to improve sender score.
Focus on engaging content and clear calls to action to foster positive recipient interaction.
Common pitfalls
Assuming a new IP address will automatically fix underlying email sending practice issues.
Ignoring spam complaints or low engagement metrics, which severely damage domain reputation.
Failing to monitor blocklists (or blacklists) for both IP and domain listings.
Not understanding that different mailbox providers might weigh IP and domain reputation differently.
Expert tips
Remember that domain reputation is generally more permanent and harder to reset than IP reputation.
For B2B sending, both IP and domain reputation remain critical, but domain often holds more weight for content filtering.
Consider a phased approach to DMARC implementation, starting with a 'p=none' policy.
Actively solicit feedback from recipients to understand and improve email engagement.
Expert view
Expert from Email Geeks says a new IP address was always a temporary fix if underlying sending practices didn't change.
2019-01-17 - Email Geeks
Marketer view
Marketer from Email Geeks says that wanting something to be true does not make it true, regardless of who told you otherwise at a conference.
2019-01-17 - Email Geeks
Key takeaways for email deliverability
IP reputation and domain reputation are two essential pillars of email deliverability, each contributing uniquely to your sending success. IP reputation establishes the credibility of your sending infrastructure, influencing the initial connection and acceptance of your emails by recipient servers. Domain reputation, on the other hand, reflects the trustworthiness of your brand, dictating whether your messages land in the inbox or are filtered as spam.
While some ISPs might prioritize one over the other, especially with the growing emphasis on domain-based signals, a holistic approach to email deliverability demands attention to both. By implementing robust email authentication, maintaining clean lists, sending valuable content, and continuously monitoring your reputation metrics, you can ensure your emails consistently reach their intended audience.
Gmail and 
Yahoo that your brand is legitimate and sends desired communications. Many major providers today place significant weight on domain reputation. You can often see a summary of your domain's reputation with tools like Google Postmaster Tools, which provides insights into your sending reputation metrics.
Google properties, helping you identify and address issues before they significantly impact your campaigns. Maintaining both positive IP and domain reputations is the key to consistent inbox delivery.
