MHTML

This article is about the mhtml webarchive format. For Mason file extension .mhtml, see Mason (Perl).

MHTML (MIME HTML)

Filename extension	.mht, .mhtml
Internet media type	multipart/related
Type of format	Markup language
Extended from	HTML
Standard(s)	RFC 2557 (proposed 1999)

MHTML, short for MIME HTML, is a web page archive format used to combine resources that are typically represented by external links (such as images, Flash animations, Java applets, audio files) together with HTML code into a single file. The content of an MHTML file is encoded as if it were an HTML e-mail message, using the MIME type multipart/related. The first part of the file is normally encoded HTML; subsequent parts are additional resources identified by their original URLs and encoded in base64. This format is sometimes referred to as MHT, after the suffix .mht given to such files by default when created by Microsoft Word, Internet Explorer, or Opera. MHTML is a proposed standard, circulated in a revised edition in 1999 as RFC 2557.

Browser support

Some browsers support the MHTML format, either directly or through third-party extensions, but the process for saving a web page along with its resources as an MHTML file is not standardized. Due to this, a web page saved as an MHTML file using one browser may render differently on another.

Internet Explorer

Microsoft Internet Explorer was the first browser to support saving web pages with all their resources to a single MHTML file as of its version 5.0 released in 1999.

Opera

Support for saving a web page with its resources as an MHTML file was made available in the Opera 9.0 web browser.^[1] In Opera 9.50, the default saving format for the "Save as" function is MHTML.

Firefox

Mozilla Firefox requires an extension to be installed to read and write MHT files. MAFF [1] and UnMHT [2] are examples. The MAFF and UnMHT extensions were formerly (in 2006) reported to have compatibility issues with opening files saved by them in Internet Explorer.^[2]

Files that are totally compatible with Internet Explorer and other browsers are created by versions 0.14 and later of the maf extension.^[3][4][5] Internet Explorer-created MHT files render perfectly, and rendering of the divergent Opera-created MHT files has been gradually improved.^[6][7][8]
UnMHT (version 5.0.0 or greater) offers partial support for MHT files exported from Microsoft Office applications.

Although Firefox does not currently (v3.6.3) include support for MHTML without the use of add-ons, there is source code available for viewing MHTML files within the related Thunderbird project, indicating that future support in Mozilla software such as Firefox may become available without such add-ons. MHTML support has been filed as an unsolved issue within the Firefox project since 1999,^[9] while progress in fixing it seems to be slow moving.

Safari

As of version 3.1.1 (released 2008-05-28) onwards, Apple Inc.'s Safari web browser does not support the MHTML format at all.

There is a workaround UnMHT port for Safari available^[10] based on the SIMBL application enhancement loader^[11] and GreaseKit.^[12]

Konqueror

As of version 3.5.7 (released 2007-05-02), KDE's Konqueror web browser does not support MHTML files. (There is a side project mhtconv that lets one use MHTML with Konqueror for both 3.x and 4.x KDE branches).

ACCESS NetFront

NetFront 3.4 (on devices such as the Sony Ericsson K850) can view and save MHTML files.

Google Chrome

Viewing MHTML files in the recent versions of Google Chrome is supported, but still not for saving.

Editing support

All versions of Microsoft Word since Word 2002 can open and save MHTML documents.^[13][14] A converter is available from Microsoft to enable Word 2000 to open MHTML files,^[15] and an add-on is available to allow it to save MHTML files.^[16]

MHTML is also supported by Microsoft Office Viewers^[17][18] in Microsoft Word, Microsoft Publisher, Microsoft Excel, and Microsoft PowerPoint.^[19] Microsoft's HTML editors, such as FrontPage, Expression Web, and SharePoint Designer, do not support editing MHTs.

A Windows application called Blocknote supports editing MHTs.^[20]

On the Linux platform, a utility called kmhtConvert is available to convert MHTML files to the KDE Web Archive format.^[21]

See also

• An alternative for attaching resources to an HTML document is the Data: URI scheme defined in IETF standard RFC 2397.
• In January 2011 Microsoft announced^[22][23] a vulnerability in all then-supported versions of Windows (XP SP3, 7, Vista, Server 2003, Server 2008) related to MHTML.

References

1. ^ Santambrogio, Claudio (10. March 2006). "…and one more weekly!". Opera Software. http://my.opera.com/desktopteam/blog/show.dml/172375. Retrieved 2009-05-15. 
2. ^ gardenerstouch (August 12, 2006). "Feature Request: Support MS Web Archive Files". MozillaZine. http://forums.mozillazine.org/viewtopic.php?p=2554347&sid=7311c84eb2fe5bbbdcdbf9d5e35c39a0. Retrieved 2011-03-17. 
3. ^ "maf.mozdev.org/changelog". http://maf.mozdev.org/changelog.html. Retrieved 2011-03-17. 
4. ^ "maf.mozdev.org/documentation". http://maf.mozdev.org/documentation.html. Retrieved 2011-03-17. 
5. ^ "maf.mozdev.org/screenshots". http://maf.mozdev.org/screenshots.html. Retrieved 2011-03-17. 
6. ^ "maf.mozdev.org/changelog". http://maf.mozdev.org/changelog.html. Retrieved 2011-03-17. 
7. ^ "maf.mozdev.org". http://maf.mozdev.org/. Retrieved 2011-03-17. 
8. ^ "maf.mozdev.org/screenshots". http://maf.mozdev.org/screenshots.html. Retrieved 2011-03-17. 
9. ^ Mozilla Firefox bug 18764
10. ^ "UnMHT for Opera/Safari". UnMHT. 2008-06-05. http://www.unmht.org/os_unmht/en_index.html. Retrieved 2009-05-10. 
11. ^ "SIMBL". 2007-10-17. http://culater.net/software/SIMBL/SIMBL.php. Retrieved 2009-05-10. 
12. ^ "greasekit". google. http://code.google.com/p/greasekit. Retrieved 2009-05-10. 
13. ^ "Convert legal documents to different word processing formats". Microsoft. http://office.microsoft.com/en-us/word/HA010744571033.aspx. Retrieved 2009-05-15. 
14. ^ "Saving a document in a file format that cannot support specific features". Microsoft. http://office.microsoft.com/en-us/word/HP010500241033.aspx?pid=CH060829791033. Retrieved 2009-05-15. 
15. ^ "WD2000: Microsoft Word-Webarchivkonverter for Word 2000". Microsoft. 5. August 2004. http://support.microsoft.com/kb/251336. Retrieved 2009-05-15. 
16. ^ "WD2000: Microsoft Office 2000 Web Archive Add-on Available". Microsoft. August 5, 2004. http://support.microsoft.com/kb/252472/EN-US/. Retrieved 2009-05-15. 
17. ^ "Download Details: Word Viewer 2003; Overview Section". Microsoft. 8/9/2005. http://www.microsoft.com/downloads/details.aspx?FamilyID=95e24c87-8732-48d5-8689-ab826e7b8fdf&DisplayLang=en#Overview. Retrieved 2009-05-15. ^{[dead link]}
18. ^ "Download Details: Word Viewer; Overview Section". Microsoft. 2007-09-26. http://www.microsoft.com/downloads/details.aspx?FamilyID=3657ce88-7cfa-457a-9aec-f4f827f20cac&displaylang=en. Retrieved 2009-05-15. 
19. ^ "About single file Web pages (MHTML)". Microsoft. http://office.microsoft.com/en-us/word/HP030776471033.aspx. Retrieved 2009-05-15. 
20. ^ "BlockNote.Net Features". BlockNote. http://blocknote.net/features.shtml. Retrieved 2009-05-15. 
21. ^ Spiros, Georgaras (Aug 7 2007). "kmhtConvert". KDE-apps. http://www.kde-apps.org/content/show.php?content=14315. Retrieved 2009-05-15. 
22. ^ "Vulnerability in MHTML Could Allow Information Disclosure". Microsoft. 2011-01-28. http://www.microsoft.com/technet/security/advisory/2501696.mspx. 
23. ^ "New Critical Bug In All Current Windows Versions". Slashdot. 2011-01-28. http://slashdot.org/story/11/01/29/0050223/. 

External links

• MHTML standard explained
• RFC 2557 (1999) — MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)
• RFC 2110 (1997, Obsolete) — MIME E-mail Encapsulation of Aggregate Documents, such as HTML (MHTML)
• MHT-rip - A program to view MHTML files on Linux