From

The From HTTP header is a request header that indicates the user’s email address who is responsible for making the request. This header is primarily used for logging purposes and for identifying the user in case any issues arise from the request.

Syntax

The From header has a simple syntax, consisting of an email address enclosed within angle brackets (< and >). Here’s the general syntax of the From header:

From: <user@example.com>

It’s important to note that the From header should not be confused with the Sender or Reply-To headers used in email messages. The From header is specifically used in HTTP requests and is not related to email protocols like SMTP.

Usage

The From header is typically used in automated processes, such as web crawlers or monitoring tools, to provide a point of contact for the website administrators. It allows the administrators to identify the source of the request and reach out to the responsible party if necessary.

Here’s an example of an HTTP request that includes the From header:

GET /example-page HTTP/1.1
Host: www.example.com
From: <webmaster@example.com>
User-Agent: ExampleCrawler/1.0

In this example, the From header indicates that the request is being made by the webmaster@example.com email address. The server can use this information for logging purposes or to contact the webmaster if there are any issues with the request.

It’s worth mentioning that the From header is not commonly used in regular browser requests, as it may raise privacy concerns. Moreover, many websites and servers do not rely on the From header, so its usage is limited.

Handling the From Header in Responses

While the From header is a request header, servers can also check for its presence and handle it accordingly. For instance, a server may decide to log the email address found in the From header or use it to send notifications in case of errors or issues.

Here’s an example of an HTTP response that acknowledges the presence of the From header in the request:

HTTP/1.1 200 OK
Date: Wed, 16 Feb 2022 10:00:00 GMT
Content-Type: text/html; charset=UTF-8
Content-Length: 12345
Server: ExampleServer/1.0
X-From-Header-Acknowledged: true

In this example, the server includes a custom X-From-Header-Acknowledged header in the response to indicate that it has recognized and processed the From header from the request.

Summary

The From HTTP header is a request header that provides an email address representing the user responsible for the request. Its primary purpose is to offer a point of contact for website administrators in case of issues or concerns related to the request.

The From header has a simple syntax and is mainly used in automated processes like web crawlers or monitoring tools. While not commonly used in regular browser requests, servers can still acknowledge and handle the From header in their responses when necessary.