Showwing mht in iframe does not work

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HTML

PHP

When i load an mht file in an iframe i get to see te source not the content

the code i use is

<iframe src='Sponsors 2019.mht' width='100%'>
<p>not compat</P>
</iframe>

i want to see the content of the file but i only get to see the source

What I have tried:

i already tryed to load it on an synology server and local with XAMPP