MHT files are much easier to export and share as all the associated HTML code and images are zipped in one file which can be directly opened in IE. Desktop Search programs like Google and MSN can index the content of mht files. Infact, most of the Microsoft Office programs like Word, OneNote, Powerpoint or Infopath can publish documents directly in mht formats. So an InfoPath 2003 document saved as MHT file can be opened even on a computer that doesn't have Infopath installed.
How to read and write .mht file formats in Firefox ?
Though Firefox doesn't provide native support for viewing or writing MHTML files, the Mozilla Archive Format (MAF) Firefox extension can help you. Once installed in Firefox, this extension lets you save Web pages in the open-source .MAFF format. It can also read and write .MHT files, which IE users can open.
However, the MAF Firefox extension requires Firefox 1.5+. If you are on a previous version, you can either install the View in IE or IE Tab extension.
In MHT files, all relative links in the Web page are remapped and the embedded content is included in the .mht file, rather than being saved in a separate folder. The absolute references or hyperlinks on the Web page remain unchanged and the .mht file is viewed using Internet Explorer.