Do images linked from your domain in spam emails cause deliverability issues?
Michael Ko
Co-founder & CEO, Suped
Published 23 May 2025
Updated 19 Aug 2025
7 min read
Discovering that images linked from your domain are appearing in spam emails can be an alarming situation. It raises immediate concerns about your brand's reputation and, more critically, your email deliverability. This practice, often called hotlinking or illegitimate embedding, means that spammers are directly referencing image files hosted on your servers within their unsolicited messages. While you're not sending the spam, your infrastructure is inadvertently supporting it.
The core question is whether this activity can negatively impact your legitimate email campaigns. The short answer is yes, it absolutely can. Email service providers and mailbox providers heavily rely on domain reputation to determine whether an email is trustworthy. When your domain is associated with spam, even indirectly through linked content, it can trigger filters and cause your own emails to be sent to the spam folder or even blocked entirely.
This situation is more complex than simply having a high image-to-text ratio or large image files, which are common deliverability concerns. Here, your domain's integrity is at stake because it's being implicated in malicious activity. Understanding the mechanisms behind this problem and how to protect your domain is essential for maintaining strong email deliverability.
How spammers use linked images
Spammers use images linked from external domains for several reasons. Often, it's to bypass rudimentary spam filters that primarily analyze text content. By embedding an image that conveys their message, they aim to make the email appear less suspicious to basic filters. The unfortunate part for legitimate senders is that these images act like digital fingerprints. If an image is consistently found within spam, it starts to acquire a poor reputation.
When your image files are hotlinked (or illegitimately embedded) into spam emails, it creates an association between your domain and the spammer's activities. Mailbox providers, using sophisticated algorithms, track patterns and content. If your image URL, which points back to your domain, is repeatedly seen in emails flagged as spam by recipients, your domain's reputation will suffer. This can lead to a domino effect where even your legitimate emails are viewed with suspicion.
This issue extends beyond just image reputation. The domain from which the image is served gains a reputation score, just like the sending domain of an email. If that image-hosting domain is frequently associated with spam, it can be added to internal or external blocklists (also known as blacklists). This directly impacts your ability to reach the inbox, as messages containing elements from blocklisted domains are often rejected or sent to junk folders. Understanding how your email domain reputation is built and maintained is crucial here.
The impact on your domain reputation
The primary consequence of your images being used in spam is a damaged sender reputation. Mailbox providers like Google and Yahoo track various signals to assess sender legitimacy, including the reputation of all domains linked within an email, not just the sending domain. If your image-hosting domain accrues negative signals due to spammer activity, it directly impacts your overall sender score. This is akin to a Google email sender guideline that warns against spam reports.
A tarnished reputation leads to a higher likelihood of your emails being flagged as spam. This can manifest in several ways: messages landing in junk folders, deferrals, or outright rejections. Even if you have robust email authentication (SPF, DKIM, DMARC) in place, a poor content reputation stemming from hotlinked images can undermine these efforts. It highlights why content reputation, which includes linked assets, is a significant factor in overall deliverability.
Beyond deliverability, there's also the issue of bandwidth consumption and potential legal or compliance risks if your infrastructure is perceived to be aiding spam. While the impact of images on deliverability has evolved, some common misconceptions persist, as noted in discussions about image-only emails and deliverability. However, active abuse of your domain via hotlinking is a distinct and serious concern that requires direct action.
Mitigating the risks
Mitigating the risk of hotlinking and protecting your domain's reputation requires a proactive approach. First, identify which images are being hotlinked and from where. This might involve checking your server logs or content delivery network (CDN) access logs for suspicious referral headers or unusually high traffic to specific image URLs from unexpected sources. Once identified, you can take steps to block this unauthorized usage.
One effective technical measure is to implement hotlink protection on your web server or CDN. This can involve configuring your server to only serve images when the request comes from a specific set of allowed referrer domains (i.e., your own website or legitimate email sending platforms). If the referrer doesn't match, the image request is denied, or a placeholder image is served instead. This directly addresses the problem of image or link hijacking.
Additionally, if specific image URLs are consistently being abused, consider replacing those image files or their URLs. This breaks the link for spammers while allowing you to continue using similar content in your legitimate emails. Regularly reviewing your web server or CDN logs for unusual access patterns to image directories can help you detect such activities early on.
While preventing this entirely can be challenging, especially if you also use these images in legitimate emails, proactive monitoring and quick action are key. For instance, some community discussions highlight the possibility of spam filters flagging malicious links or code in signatures, underscoring the broad risk of unmonitored external content.
Views from the trenches
Best practices
Implement hotlink protection on your web server or CDN to restrict unauthorized image usage, serving images only to allowed referrers.
Regularly monitor your server logs for suspicious access patterns to image URLs, especially from unexpected or high-volume sources.
If an image is found in spam, immediately replace the image file or change its URL to break the spammer's link and prevent further damage.
Maintain strong overall domain reputation by adhering to email best practices, even when dealing with hotlinking issues.
Common pitfalls
Ignoring reports of your domain’s images appearing in spam emails, assuming it won't impact your legitimate sending.
Failing to implement hotlink protection, leaving your images vulnerable to unauthorized use and reputation damage.
Not having a system to quickly identify and depublish abused image URLs, allowing spammers to continue leveraging your assets.
Over-relying on email authentication alone, without considering the impact of content reputation from linked assets.
Expert tips
Invest in real-time blocklist (or blacklist) monitoring to quickly detect if your domain or IP is listed, especially due to hotlinking.
Consider hosting promotional images on a separate subdomain with tighter security controls to isolate potential reputation issues.
Educate your team on the risks of image hotlinking and best practices for image management in emails and on websites.
Perform regular deliverability tests to identify if linked content is impacting inbox placement before it becomes a major problem.
Expert view
Expert from Email Geeks says that having your domain's images included in spam emails can negatively affect your sending reputation.
Dec 10, 2019 - Email Geeks
Marketer view
Marketer from Email Geeks recommends restricting where images can be linked from on your web server or CDN.
Dec 10, 2019 - Email Geeks
Protecting your email reputation
In conclusion, yes, images linked from your domain in spam emails can cause significant deliverability issues. This stems from the fact that your domain, and by extension your sender reputation, becomes associated with malicious activity. Mailbox providers interpret the presence of your domain's assets in spam as a negative signal, potentially leading to your legitimate emails being misdirected to the junk folder or blocked entirely.
Proactive measures such as implementing hotlink protection, regularly monitoring your server logs, and quickly replacing compromised image URLs are crucial. By taking these steps, you can minimize the impact of hotlinking on your domain and protect your email deliverability. Remember, maintaining a strong sender reputation involves safeguarding all aspects of your domain's online presence, not just your email sending practices.
Staying vigilant against such threats is an ongoing part of email deliverability management. Leveraging tools for blocklist monitoring and understanding why your emails go to spam can provide the insights needed to maintain healthy inbox placement rates.
Google and 
Yahoo track various signals to assess sender legitimacy, including the reputation of all domains linked within an email, not just the sending domain. If your image-hosting domain accrues negative signals due to spammer activity, it directly impacts your overall sender score. This is akin to a Google email sender guideline that warns against spam reports.
