Convert MHTML to HTML using C#

Question

I was tasked to embed a mHtml into an email body. The issue is that mhtml is not a normal html file so I cannot embed it directly to the email.

How can I do to convert the mhtml into a html file?

Thanks

Answer 1

I found the solution on this link :

Original (Dead) Link

Archived Link

The solution was to extract the HTML encoded as Base64 inside the MHTML.

var decoded_text = new StringBuilder();
using (var reader = new StreamReader(mhtFile))
{
    while (!reader.EndOfStream)
    {
        var line = reader.ReadLine();
        if (line != "Content-Transfer-Encoding: base64") continue;
 
        reader.ReadLine(); //chew up the blank line
        while ((line = reader.ReadLine()) != String.Empty)
            if (line != null)
                decoded_text.Append(line);
        break;
    }
    return Encoding.UTF8.GetString(
               Convert.FromBase64String(decoded_text.ToString())));
}

EDIT: Fixed to support diacritics letters in html suggested by Otas