Outlook for Windows has long had an option to view HTML pages in a browser. When you click the InfoBar message “If there are problems with how this message is displayed, click here to view it in a web browser.” or open the message using the View in Browser command, Outlook saves the messages as an MHT file, which saves the HTML and images in a single file.
Unfortunately, only Internet Explorer supports properly rendering these MHT files as HTML files. Now that Microsoft removed Internet Explorer from Windows 10, how do you view messages in a browser?
Easy: enable the option in Edge to “Allow sites to be reloaded in Internet Explorer mode”. It’s in Edge Settings, under Default browser section.
If you aren’t using Edge as your default browser, you DO NOT need to change your default browser to Edge, only enable the option to allow sites to load in IE mode. Outlook will use Edge to view the MHT file.
To enable Internet Explorer mode, open Edge’s Settings and select Default Browser on the left. Under “Allow sites to be reloaded in Internet Explorer mode”, set it to Allow. Once you make this change, choosing “view it in a web browser” in Outlook will open the message in Edge.