What is MIME type "message/x-emlx"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

message/x-emlx is a MIME type used by Apple's Mail application. It represents an individual email message stored in a file with a EMLX extension. The file holds not only the message body but also its header information and sometimes references to attachments.

This format allows email clients to process each message as a discrete file. It is not standardized like some other MIME types, but it works well in macOS environments.
It uses plain text with extra metadata to keep track of email details.

Primary use: Storing individual email messages from Apple Mail.
Archival: Supports email backup and migration on macOS.
Processing: Helps email clients easily open, read, and sort messages.

Note: Although the format is text-based, some sections might be encoded to handle special characters or attachments. For more on MIME types, visit the MIME Wikipedia article.

Associated file extensions

.emlx

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: message/x-emlx

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="message/x-emlx">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');    
    
    http.createServer((req, res) => {    
      res.setHeader('Content-Type', 'message/x-emlx');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.emlx

FAQs

What is the difference between .eml and .emlx files?

Standard .eml files usually utilize the MIME type message/rfc822 and contain raw email data compatible with most clients like Outlook or Thunderbird. The .emlx format (message/x-emlx) is specific to Apple Mail and includes a byte-count header and XML metadata footer for internal indexing purposes.

How do I open a message/x-emlx file on Windows?

You can often rename the file extension from .emlx to .eml to open it with Microsoft Outlook or Mozilla Thunderbird. Because the format is largely text-based, you can also view the raw contents using a simple text editor like Notepad, though you will see extra metadata.

How should I configure Nginx to serve .emlx files?

Add the MIME type definition to your mime.types file or within the specific server block configuration. Use the directive types { message/x-emlx emlx; } to ensure the server sends the correct Content-Type header to the client.

Is message/x-emlx a standard IANA MIME type?

No, the x- prefix signifies that it is a non-standard, proprietary type defined by Apple for use within macOS. For standardized email interchange across the internet, the generic message/rfc822 type is preferred.

Why does a text editor show numbers at the start of an .emlx file?

The message/x-emlx format begins with a byte count (an integer) on the first line indicating the length of the email message content. This is used by Apple Mail for indexing and parsing but is not part of the actual email body.

How do I add support for emlx files in Apache?

You can enable support by adding the AddType directive to your .htaccess file or main configuration. Add the line AddType message/x-emlx .emlx so that browsers recognize the file type correctly when users download it.

General FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.