What is the HTTP Referrer-Policy header and how does it relate to email sending and hosted images?

Email marketer from StackExchange describes that the referrer policy is important for maintaining user privacy. Many browsers default to allowing all Referer information to be sent, including potentially sensitive information like user IDs or session tokens. Setting a stricter Referrer-Policy helps mitigate this leakage.

Email marketer from Cloudflare states that the Referrer-Policy header lets sites have more control over this data. Setting the policy correctly helps to prevent this sensitive data from leaking. It can protect users' privacy and prevent malicious actors from abusing the data.

Email marketer from DNSimple describes that when a user clicks a link from one website to another, the browser sends an HTTP Referer header to the destination server. The header contains the URL of the referring page. Setting a Referrer-Policy protects the privacy of your users and the security of your website by limiting the information that is sent in the Referer header.

Marketer from Email Geeks explains that the request to the image goes to a server that would contain the Referrer Policy from the requested image.

Email marketer from Stack Overflow explains that the Referrer-Policy can affect image requests if those requests redirect or rely on the Referer header for tracking or authentication. A restrictive policy might prevent the image server from knowing where the request originated, potentially breaking functionality or analytics.

Marketer from Email Geeks explains that the HTTP Referrer-Policy header is a security header that controls how much information about the originating URL of a request is included in the Referer header and how different values for the Referrer-Policy header dictate different behaviors. The Referer header is sent by the browser to indicate the URL of the web page from which the current request originated, enhancing privacy and security by controlling the amount of information shared.

Email marketer from Troy Hunt's Blog discusses the security implications of the Referer header and advocates for using a strong Referrer Policy. He points out that the Referer header can inadvertently leak sensitive information and emphasizes the importance of configuring the header correctly to protect user privacy and prevent attacks.

Email marketer from Email Marketing Forum raises a point about email tracking pixels. If emails contain tracking pixels (small, invisible images), the request for these images might be affected by the Referrer-Policy. A restrictive policy could prevent the email sender from knowing which website the email recipient was visiting when they opened the email.

Email marketer from KeyCDN explains that a Referrer-Policy header allows you to decide what information, if any, should be passed along to another website. By using the Referrer-Policy HTTP header, you can prevent certain information from being sent to other sites when a user clicks a link on your site.

Email marketer from OWASP describes Referrer Policy as a way to control information that a website passes along when a user clicks a link that leads them away from the site. The HTTP Referer header can contain sensitive information about the user and the website they are visiting. By implementing the Referrer-Policy HTTP header, websites can control the amount of information that is included in the Referer header.

Marketer from Email Geeks suggests that the HTTP Referrer-Policy header might be related to hosted images.

Email marketer from Scott Helme's Blog explains that the Referrer-Policy header is a crucial security measure. It allows websites to control the information passed in the Referer header when users navigate to other pages. This can prevent sensitive data from being exposed to third parties and helps mitigate risks like cross-site scripting (XSS) attacks.

Email marketer from Reddit suggests that Referrer-Policy becomes relevant with CDNs. If images or other resources are served through a CDN, the CDN might use the Referer header for caching or security purposes. A restrictive policy could impact CDN performance or prevent access to resources.

Expert from Email Geeks initially states that images don’t contain links, so the HTTP Referrer-Policy header wouldn’t do anything, but then agrees that it could be relevant if the image request results in a 302 redirect to a CDN.

Expert from Word to the Wise explains that the HTTP Referrer-Policy header is used to control how much information is passed along with requests for resources, like images hosted on a server, which can impact email marketing if not properly configured. A restrictive referrer policy may limit the ability to track email opens or identify user behavior based on image requests.

Documentation from IETF outlines the specifics of the Referrer Policy specification. It defines the syntax and semantics of the Referrer-Policy HTTP header and the referrerpolicy attribute. The specification also defines the processing model that user agents (browsers) must follow when handling these directives.

Documentation from Google Developers highlights how the Referrer-Policy affects web analytics. Many analytics tools rely on the Referer header to track traffic sources. Setting a restrictive policy can lead to inaccurate or incomplete analytics data, making it harder to understand user behavior and measure marketing effectiveness.

Documentation from W3C outlines the specifics of the Referrer Policy standard. It defines the different policy directives (e.g., no-referrer, origin, unsafe-url) and their impact on the Referer header. It also details the process by which browsers determine which policy to apply to a given request, considering factors like meta tags and the referrer attribute.

Documentation from MDN Web Docs explains that the HTTP Referrer-Policy header controls how much referrer information (sent via the Referer header) should be included with requests. It governs the information websites receive about the origin of traffic and can enhance privacy and security by limiting the data shared.