What is MIME type "application/x-mspublisher"?

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

application/x-mspublisher is the MIME type for files produced by Microsoft Publisher. These files contain desktop publishing data such as page layouts, text, images, and graphics optimized for printing or digital distribution.

File Identification: It signals that the file is a publication document.
System Handling: Operating systems and applications use this MIME type to launch the correct program.
Usage Context: It's used when sharing or emailing documents created in Microsoft Publisher.
Document Features: The files store design elements and formatting that standard text editors typically cannot process.

The MIME type is associated with the file extension PUB. More information can be found in resources like the Microsoft Publisher article.

Associated file extensions

.pub

Usage Examples

HTTP Header

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


    Content-Type: application/x-mspublisher

HTML

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


    <a href="file.dat" type="application/x-mspublisher">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', 'application/x-mspublisher');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.pub

FAQs

Can web browsers display application/x-mspublisher files directly?

No, modern web browsers like Chrome, Firefox, and Edge cannot natively render Microsoft Publisher files. When a server sends the application/x-mspublisher header, the browser will typically prompt the user to download the file rather than displaying it. To view these documents in a browser, they should be converted to a web-friendly format like PDF (application/pdf).

How do I configure Apache to serve .pub files correctly?

You can ensure your Apache server sends the correct MIME type by modifying your .htaccess file or the main configuration. Add the following line: AddType application/x-mspublisher .pub. This ensures that when users request a file with the .pub extension, the server identifies it correctly.

What software is required to open an application/x-mspublisher file?

The primary software for this MIME type is Microsoft Publisher, which is part of some Microsoft Office editions. If you do not have Publisher, open-source alternatives like LibreOffice Draw can often open and edit these files. You can verify the file type by checking the .pub extension.

How do I set up this MIME type in Nginx?

For Nginx, you need to update the mime.types file, which is usually located in /etc/nginx/. Add the following entry inside the types { } block: application/x-mspublisher pub;. After saving the file, reload Nginx to apply the changes.

What does the 'x-' prefix mean in application/x-mspublisher?

The x- prefix indicates that this is a non-standard or proprietary MIME type, originally defined outside of the IANA standardization process. While it is widely recognized by Windows systems and email clients for identifying Microsoft Publisher documents, it is specific to the Microsoft ecosystem.

Is it safe to open files sent as application/x-mspublisher?

You should exercise caution, as Microsoft Office documents can contain macros or embedded scripts that may be malicious. Always ensure the file comes from a trusted source before opening it. If you only need to read the content, converting it to a static image or PDF is a safer alternative.

Why does my .pub file look like random characters in the browser?

This usually happens if the web server is misconfigured and serves the file as text/plain instead of application/x-mspublisher. The browser attempts to read the binary layout data as text, resulting in garbled output. Correcting the MIME type on the server will force the browser to download the file instead.

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.