We have found one software suitable in our database for this conversion.
Since latest version of Microsoft Word can directly open PDF documents and also supports saving to MIME HTML (.mht) format, the program would be probably your best and easiest choice for pdf to mht conversion.
Another possibility would be to first convert the PDF to text (or copy paste) and save it it some text editor / word processor that also supports MIME HTML format.
PDF
A pdf file extension is mainly used for Adobe Portable document format, commonly referred to as PDF. All programs that create some sort of documents or projects offer the possibility to export their format to PDF format. A free PDF viewer (Adobe Reader) is available for download from Adobe website.
MHT
An mht file extension is associated with the Mime HTML files. MHTML is web archive format used to bind resources and HTML code into a single file. Used mainly on internet and openable with every web browser.