Should the X-originating-IP header be removed for email deliverability and security?
Michael Ko
Co-founder & CEO, Suped
Published 16 May 2025
Updated 16 Aug 2025
8 min read
Email headers are a treasure trove of information, providing a detailed log of an email's journey from sender to recipient. Among these, you might often spot the X-Originating-IP header. This particular header isn't part of the standard set defined by internet RFCs, meaning it's a custom, non-standard header that many mail systems choose to add.
Historically, the X-Originating-IP header was quite useful for tracking the actual source of an email, especially for large webmail providers trying to combat spam. It could pinpoint the specific IP address from which a message originated, aiding in abuse detection. However, its utility in modern email security and deliverability practices is often debated.
Today, concerns about privacy and potential security implications have led many to question whether this header should be removed from outbound emails. While it offers some forensic value, its presence might expose information that some organizations prefer to keep private. This article explores the various facets of the X-Originating-IP header, weighing its benefits against the risks to help you make an informed decision for your email infrastructure.
Understanding the X-Originating-IP header
The X-Originating-IP header is essentially a stamp that an email server or client adds to an outgoing message, indicating the IP address from which the email client connected to the server. This often means it records the sender's public IP address at the moment of sending. While it is not mandatory for email transmission, many systems include it for various reasons, mainly historical ones related to abuse prevention.
Its primary utility, as mentioned, lies in the ability to trace the actual origin of an email. For more details on its historical use, you can read about the utility of X-Originating-IP in email headers. This was particularly relevant in the early days of the internet when identifying spammers was a more rudimentary process. Mailbox Providers (MBPs) like AOL and Hotmail used it to selectively block users based on their assigned dial-up IP addresses.
However, it's important to note that much of the information provided by X-Originating-IP is often duplicated or made redundant by the standard Received headers. These standard headers are added at each hop an email takes through different servers, each adding its own IP and timestamp. This means that even without X-Originating-IP, a forensic investigator can often trace the email's path.
Security and privacy implications
The primary concern with the X-Originating-IP header revolves around privacy. By including the sender's IP address, it can potentially reveal their precise location or even their home network IP, if the email is sent from a personal device. This level of exposure might not align with modern privacy standards or corporate policies, particularly for organizations handling sensitive communications.
From a security standpoint, exposing internal IP addresses or details about your network topology, even indirectly, is generally seen as a potential vulnerability. While the risk might be minor compared to other attack vectors, it's still information that an organization might prefer to conceal from the public internet. Some mail systems, like Microsoft Exchange, allow administrators to create transport rules to remove this header for security reasons. You can find more information on how Exchange Online addresses this issue.
Many major Mailbox Providers (MBPs) have already taken steps to address these concerns. For instance, Microsoft removed the X-Originating-IP header from Hotmail years ago for security and privacy reasons. This trend suggests a move towards minimizing exposed information in email headers that isn't strictly necessary for mail routing and authentication. The X-Originating-IP header's flaws and privacy concerns are well documented.
Pros of X-Originating-IP
Abuse tracking: Helps identify the source of spam or malicious activity for forensic analysis.
Filtering aid: Historically used by older email systems, such as AOL and Hotmail, for filtering decisions based on the client IP.
Reputation for shared IPs: In specific contexts, it can provide more granular source information, potentially influencing reputation positively for mail from shared IP addresses.
Cons of X-Originating-IP
Privacy exposure: Leaks the sender's specific IP address, potentially revealing personal location or internal network details.
Security risks: May expose elements of internal network topology or server configuration, though often a minor risk.
Redundancy: Much of the information it carries is already present in the standard Received headers, making it often unnecessary.
Impact on email deliverability
When considering email deliverability, the direct impact of the X-Originating-IP header on inbox placement is generally minimal for most modern filtering systems. Contemporary email filters prioritize robust authentication protocols such as SPF, DKIM, and DMARC. These mechanisms are far more influential in determining an email's legitimacy and sender reputation than custom headers like X-Originating-IP. To learn more about its impact, refer to our guide, Does x-originating-ip impact email deliverability?
While it doesn't usually affect deliverability directly, its presence could, in rare cases, contribute to a spam score if the IP listed in this header is on a public blacklist (or blocklist). However, this is far less common and less impactful than if your main sending IP (the one in the Received header) were blocklisted. For a deeper dive into how blocklists work, read an in-depth guide to email blocklists.
Ultimately, email filters will scrutinize your messages regardless of the presence of X-Originating-IP or any other custom header. The focus should always be on adhering to email best practices, ensuring your SPF, DKIM, and DMARC records are correctly configured, and maintaining a strong sender reputation. Google's email sender guidelines emphasize these core authentication methods for improved delivery.
Considering X-Originating-IP and your email program
Focus on core authentication: Prioritize a strong DMARC policy, correctly configured SPF, and valid DKIM signatures for optimal email deliverability.
Monitor your main sending IPs: Ensure your primary outbound IP addresses (the ones in the Received headers) are not on any major blocklist (blacklist).
Understand your infrastructure: If your mail system (e.g., Zimbra) adds this header, assess if the exposed IP is an internal network address or a client's public IP.
Deciding whether to remove the header
The decision to remove the X-Originating-IP header largely comes down to your organization's privacy and security policies. If the exposure of client IP addresses is a significant concern for your users or your business, then removing this header is a straightforward and effective way to mitigate that risk. Since its impact on deliverability is minimal, the benefits of enhanced privacy generally outweigh any perceived loss of forensic data.
There are very few scenarios where retaining the X-Originating-IP header would be genuinely beneficial for typical outbound email sending, such as transactional or marketing emails. In highly controlled internal environments or for specialized forensic analysis, it might have a niche role, but these are exceptions rather than the norm. Most email administrators will find little practical value in keeping it.
Removing this header is often a configurable option within your Mail Transfer Agent (MTA) or email server software. This usually involves setting up transport rules to strip the header before the email leaves your network. It's crucial, however, not to confuse this with removing standard Received headers, which are fundamental for email routing and can negatively impact deliverability if tampered with. To understand more about the effects of other custom headers, refer to Do X-Headers negatively impact email deliverability?
Example Exchange Online transport rule to remove X-Originating-IP headerPowerShell
Always assess the privacy implications of any non-standard headers your email system adds.
Prioritize strong email authentication protocols like SPF, DKIM, and DMARC for deliverability.
Review your Mail Transfer Agent's default header configurations to avoid unnecessary information leakage.
For shared IP environments, ensure that any headers contributing to positive reputation are understood.
Common pitfalls
Assuming removing X-Originating-IP will significantly boost email deliverability instantly.
Accidentally removing crucial standard headers, like Received headers, which can disrupt mail flow.
Not understanding which IP address (internal or external) is actually being exposed by the header.
Failing to check if your mail system relies on certain headers for bounce processing or internal routing.
Expert tips
Use a reliable email deliverability tester to check your email headers and identify any unexpected entries.
Regularly monitor your domain and IP reputation using tools like Google Postmaster Tools.
Consult your email service provider or Mail Transfer Agent documentation for specific guidance on header management.
Focus on content quality and recipient engagement, as these are primary drivers of inbox placement.
Expert view
Expert from Email Geeks says the X-Originating-IP header, when trusted, can be used in filtering decisions, particularly by older mail providers like AOL and Hotmail to selectively block customers based on their assigned dial-up IP.
2021-06-01 - Email Geeks
Expert view
Expert from Email Geeks says this header can also be used positively to improve sender reputation for mail originating from a shared IP address.
2021-06-01 - Email Geeks
Streamlining your email headers for enhanced privacy
The X-Originating-IP header is a vestige of earlier email practices, primarily designed to assist in tracing email origins for abuse detection. While it served a purpose, its relevance for modern email deliverability is minimal, as current filtering systems rely on more sophisticated authentication protocols and sender reputation signals.
The main argument for removing the X-Originating-IP header centers on privacy and, to a lesser extent, security. By removing this non-standard header, organizations can prevent the unnecessary exposure of sender IP addresses, aligning with stricter data privacy standards. For most senders, this removal introduces no adverse effects on email deliverability and can enhance overall privacy. Focus your efforts on core email authentication to improve inbox placement.
AOL and 
Hotmail used it to selectively block users based on their assigned dial-up IP addresses.
Microsoft Exchange, allow administrators to create transport rules to remove this header for security reasons. You can find more information on how Exchange Online addresses this issue.
Google's email sender guidelines emphasize these core authentication methods for improved delivery.
Zimbra) adds this header, assess if the exposed IP is an internal network address or a client's public IP.
