HowTo: Open .mht Files Including Images

Opening a file including its images does not sound particularly difficult, does it? With .mht files, however, it apparently can be difficult enough that even some network administrators cannot manage it. At least that was the case at my mother’s school.

What Are .mht Files and Where Do They Come From?

.mht files are web pages saved in Microsoft Internet Explorer. The basic idea is actually quite good: the web page, including all images or videos, is stored in a single file and can therefore easily be sent by email, for example. Unfortunately, it is a Microsoft idea and was implemented somewhat awkwardly.

Why Can’t I See the Images in the .mht File?

This problem normally occurs when the file was created on another computer. Apparently, if you create an .mht file from a web page, you can view it with its embedded images only on the PC on which the .mht file was created. If the file is opened on another computer, the images may not be displayed. This restriction exists because .mht files could otherwise be abused relatively easily for malicious content.

What Solutions Are Available?

There are solutions that involve changing several Windows Registry entries to remove the image restriction. If you are not particularly experienced with PCs, I advise against this approach. First, editing the Windows Registry is not something an ordinary user should do casually. Second, it can make your computer more vulnerable to viruses and Trojans. One such solution is described here.

To be honest, that solution did not work for me at all either. So my advice is: leave it alone.

Much Easier: Use Firefox with the “UnMHT” Add-on

The easiest solution is to open the file with Firefox. You first have to teach Firefox how to handle an .mht file, but that is far less involved than editing the Registry as described above. Your computer also remains safer.

1. Open a current version of Firefox

2. In the Firefox menu, click “Tools” and then “Add-ons”

A new window called “Add-ons” opens.

3. In this new window, click “Get Add-ons” in the top left.

4. Use the search field to look for the “UnMHT” extension and install it.

5. After UnMHT has been installed, restart Firefox.

6. Once Firefox has restarted, open your .mht file by clicking “File” in the Firefox menu, then “Open File” and selecting your .mht file.

The .mht file should now be displayed including its images. If you still have difficulties, feel free to send me a message or leave a comment.