Does x-originating-ip impact email deliverability?
Michael Ko
Co-founder & CEO, Suped
Published 17 Apr 2025
Updated 19 Aug 2025
8 min read
When delving into email deliverability, the myriad of headers within an email can sometimes feel overwhelming. One such header that occasionally sparks questions is the X-Originating-IP. It's not a standard header like Received or Message-ID, but it often appears in email headers, particularly from webmail interfaces or certain email service providers (ESPs).
This header is intended to reveal the IP address of the client (the user's computer or device) from which the email originated, rather than the IP address of the server that sent the email on its final journey. Historically, it served a purpose in identifying the true source of an email, especially for abuse investigations or tracing spam.
The critical question for anyone focused on email marketing and security is whether this X-Originating-IP has any bearing on whether your emails land in the inbox or are filtered to spam. While it once played a role in some filtering decisions, its direct impact on email deliverability today is often misunderstood and significantly diminished.
Understanding the X-originating-IP header
The X-Originating-IP header is a non-standard (or X-header) that is added by an email client or an intermediate server to identify the originating IP address of the sender's machine. Unlike the Received headers, which are added by each mail server as the email passes through, X-Originating-IP aims to pinpoint the client's actual public IP address at the point of sending. You can learn more about this header's purpose in what is the utility of X-Originating-IP.
For example, if you send an email using Outlook.com's web interface, the X-Originating-IP header might contain your home IP address. This was particularly useful in the early days of email to identify users sending spam from their personal computers, especially when their Internet Service Providers (ISPs) weren't adequately blocking outgoing email on port 25 or were experiencing abuse from compromised accounts. The X-Originating-IP header offers a way to trace problematic email campaigns directly to their source, even if the sending server is legitimate.
Below is an example of what this header might look like within an email's full header information:
Example X-Originating-IP header
X-Originating-IP: [192.0.2.123]
Despite its utility for forensic analysis and combating abuse, the X-Originating-IP header can be easily spoofed or faked by malicious actors. This inherent untrustworthiness means that receiving mail servers and spam filters generally do not rely on it as a primary factor for deliverability decisions. They typically prioritize more robust and verifiable authentication protocols like SPF, DKIM, and DMARC, along with the reputation of the actual sending IP address and domain.
Historical vs. modern filtering
In the past, especially when spam filtering technology was less sophisticated, some receiving mail servers or spam filters might have examined the X-Originating-IP header more closely. This was particularly true for personal email accounts or those originating from dynamic IP addresses (like residential broadband connections) that might have been listed on dial-up user (DUL) blocklists (or blacklists). If the IP address in this header was associated with known spam activity or a consumer IP range, it could indeed negatively affect deliverability. You can refer to this guide on what is an email blacklist for more information.
However, the landscape of email deliverability has evolved significantly. Today's spam filters and recipient mail servers are far more advanced, relying on a complex array of signals to determine an email's trustworthiness. These signals include the sender's IP reputation, domain reputation, content analysis, user engagement, and the proper implementation of email authentication protocols. The direct impact of X-Originating-IP on deliverability is largely negligible for legitimate senders using reputable ESPs or well-configured mail servers.
For the vast majority of email traffic, especially marketing and transactional emails sent through professional platforms, the X-Originating-IP header is either not present, or its content is not a primary factor in filtering decisions. Mailbox providers like Google and Yahoo are more concerned with the reputation of the IP address that directly connects to their servers and the authenticity of the sending domain. An X-Originating-IP that points to a problematic IP is generally not enough to trigger a spam classification if all other reputation and authentication signals are strong. For more on how IP reputation can affect email delivery, check out this Mailpro blog post.
However, in specific niche scenarios (e.g., highly customized, older mail configurations, or when dealing with certain legacy systems), it's conceivable that some obscure filters might still reference this header. This is, however, an increasingly rare occurrence in mainstream email delivery.
Modern Relevance and best practices
While the X-Originating-IP header itself has minimal direct impact on modern deliverability, the underlying concept of IP reputation remains paramount. The reputation of the IP address from which your emails are actually sent (the outbound IP, not the originating client IP) is a critical factor. Sending from a dedicated IP address with a strong positive reputation is beneficial, as is maintaining a good reputation on shared IPs. For more on this, check does IP address location affect deliverability.
Many major email providers, including Microsoft and Gmail, have largely moved away from relying on X-Originating-IP for primary filtering. Google'ssender guidelines, for instance, emphasize domain and IP reputation, authentication, and content. If you're using a modern ESP, they might strip this header automatically or provide options to do so. In general, removing this header can sometimes be a good practice for privacy or to prevent any legacy systems from misinterpreting the client IP.
If you are concerned about any X-header impacting your deliverability, it's generally best to focus on the main pillars of email deliverability:
Sender Reputation: Maintain a high reputation for your sending IP and domain. This is built over time through consistent sending of wanted, engaged-with emails.
Authentication: Properly implement SPF, DKIM, and DMARC. These protocols verify that you are authorized to send email from your domain, which is crucial for modern inbox placement. You can find a simple guide to DMARC, SPF, and DKIM for more information.
Content Quality: Ensure your email content is relevant, engaging, and avoids characteristics commonly associated with spam.
List Hygiene: Regularly clean your email lists to remove inactive or invalid addresses, reducing bounces and spam trap hits.
Summary of its impact
While the presence or absence of the X-Originating-IP header rarely dictates email deliverability outcomes in today's environment, understanding its role is still part of a comprehensive approach to email security and troubleshooting. For most bulk senders, focusing on the core aspects of email deliverability will yield far greater results.
Focus of older filters
Historically, some filters would scan the X-Originating-IP against blacklists (or blocklists) or classify based on IP ranges (e.g., residential IPs) if they were associated with suspicious activity or spam.
Trustworthiness of the header
This header is easily spoofed, making it an unreliable indicator for modern spam filters.
Focus of modern filters
Modern spam filters prioritize the reputation of the actual sending IP and domain, email authentication (SPF, DKIM, DMARC), content analysis, and engagement metrics.
Primary deliverability factors
A strong sender reputation, correct authentication setup, and engaging content are far more critical than the presence or value of X-Originating-IP.
In essence, while the X-Originating-IP header provided a glimpse into an email's origin, its direct relevance to email deliverability has largely faded. Focusing on establishing and maintaining a robust sender reputation through proper authentication and sending practices will have the most significant positive impact on your inbox placement.
Always prioritize consistent sending volume, segmenting your audience, and personalizing your content to foster engagement. These are the true drivers of strong deliverability in the current email ecosystem, far outweighing any concerns about this particular unofficial header.
Views from the trenches
Best practices
Regularly monitor your main sending IP and domain reputation through services like Google Postmaster Tools.
Ensure your email authentication records (SPF, DKIM, DMARC) are correctly configured and aligned.
Maintain a healthy email list by removing inactive or bouncing addresses.
Common pitfalls
Over-reliance on outdated filtering assumptions that might give too much weight to unofficial headers.
Not monitoring for actual IP or domain blacklisting (or blocklisting) events, which have a real impact.
Ignoring the importance of user engagement metrics, which are primary signals for ISPs.
Expert tips
While the X-Originating-IP header is largely ignored for deliverability today, it can still be useful for forensic analysis of spam or abuse coming from compromised client machines.
If you are an enterprise sender using Microsoft 365, you have the option to remove the X-Originating-IP header through outbound filters, which can sometimes be beneficial for privacy.
Always prioritize the reputation of the IP address that makes the final connection to the receiving mail server, as this is what truly matters for deliverability.
Expert view
Expert from Email Geeks says the X-Originating-IP header might be used for secondary received-line filtering in some specific contexts, but it's an unusual inclusion for outbound mail unless senders implicitly want it to be considered for filtering.
January 11, 2021 - Email Geeks
Expert view
Expert from Email Geeks says the X-Originating-IP header is included by default with Microsoft 365, but it can be removed using an outbound filter. They also noted that it's primarily about anti-abuse today, and most free email providers, with the exception of Gmail, still include it.
Outlook.com's web interface, the X-Originating-IP header might contain your home IP address. This was particularly useful in the early days of email to identify users sending spam from their personal computers, especially when their Internet Service Providers (ISPs) weren't adequately blocking outgoing email on port 25 or were experiencing abuse from compromised accounts. The X-Originating-IP header offers a way to trace problematic email campaigns directly to their source, even if the sending server is legitimate.
Google and 
Yahoo are more concerned with the reputation of the IP address that directly connects to their servers and the authenticity of the sending domain. An X-Originating-IP that points to a problematic IP is generally not enough to trigger a spam classification if all other reputation and authentication signals are strong. For more on how IP reputation can affect email delivery, check out this Mailpro blog post.
Microsoft and Gmail, have largely moved away from relying on X-Originating-IP for primary filtering. Google'ssender guidelines, for instance, emphasize domain and IP reputation, authentication, and content. If you're using a modern ESP, they might strip this header automatically or provide options to do so. In general, removing this header can sometimes be a good practice for privacy or to prevent any legacy systems from misinterpreting the client IP.
