If you want the file to be displayed in the browser, the user will need to have an application capable of displaying it in the browser, and you will need to set
Inline
to
true
.
If you set
Inline = false
, that forces the browser to download the file, even if it is capable of displaying it within the browser.
To display a MIME message in the browser regardless of the user's software, you'll need to parse it yourself and render the relevant parts in an HTML view. The best tool to parse the message in C# is probably
MimeKit[
^].