Mail Markup Language

From Seo Wiki - Search Engine Optimization and Programming Languages

Jump to: navigation, search


Mail Markup Language

Mail Markup Language (MML) is a markup language intended for describing and structuring the content and user agent headers of content intended for transport across the Simple Mail Transport Protocol (SMTP). In this manner MML is intended for use as a peer language to the more familiar Hypertext Markup Language (HTML) that describes and structures content across the Hypertext Transfer Protocol (HTTP).


The current specification is Mail Markup Language version 1.0 available at

Legal Status

MML contains features that are patent pending, but is itself not protected. If a patent is granted for the protected features they will be protected in the US until 17 Apr 2008 and may or may not be protected in other nations until that time. Ownership of the language specification passed from Sabre Inc. to Travelocity LLC on 16 Apr 2009. A licensing decision has not been finalized as of 17 Apr 2009.

Features Claimed for Protection

The patent application for MML claims the technology contains several novelty features[1] . Eight claims are specified for only two of those novelties specifically:

  1. Data Sessioning — MML claims novelty over the convention of using conventions of the XML meta language to identify, structure, and format data into separated scopes without the need to explicitly declare a namespace for each scope. In practice of MML this convention is exhibited by use of the session tag to constrain semantic and presentation processing to contents of the session tag so that such processing does not interfere with the processing of other session tag elements.
  2. Public Key Tag/Attribute — MML claims novelty over the convention of using an element or attribute of a markup language to distinguish the hash value representation of a public key from asymmetric cryptography without the need to send such a public as an attachment external to the text content of the transmission.


MML is the invention of Austin Cheney. Shortly after entering employment with Travelocity as a web design contributor the first official task assigned to Austin was to write the HTML code for a company-wide email newsletter for the then CEO of Travelocity, Michelle Peluso. The resultant email produced unexpected presentational results only after its transmission by the CEO. Upon researching a solution to the problem Austin claimed that there was no standard for formatting or describing content in an email and so content formatting with HTML cannot be preserved from one client software to another. According to Austin, the only solution was to define a user-agent independent scheme for formatting content with intended transmission as an email.

Design Considerations

XML Schema was chosen as the meta language for writing MML because of its immediate validation quality. Since the language is written in XML and defined by a schema validation is a requirement written into the specification. A MML document cannot be transmitted over a transmission protocol intended for use in email without violating a convention of the specification.

MML was designed primarily as a semantic describer of human language completely without regard for ease of use or visual formatting of that language. The benefit to this approach is that abbreviations and acronyms are almost entirely removed from the vocabulary of the language so that it contains more expressive and recognizable element and attribute names in ease of rapid understandability. This benefit comes at the cost of much longer element names when compared with HTML, which could result in expanded file sizes of documents. A second benefit of this approach is that MML contains significantly few element names compared to HTML 5.

MML wished to further extend semantic descriptions by informally creating a structural convention that may allow contextual interpretations of content. To achieve this objective MML uses a three layer hierarchy to define where elements may be used. The top layer is for elements that may contain other elements but never directly contain content, the second layer may contain elements and/or content, and the final layer describes content directly and may not contain elements. This approach makes use of elements extremely less flexible compared to HTML, however it prevents unintended use of the elements without directly limiting expression or structuring of content, which is a feature unavailable to HTML.

MML views accessibility as an extension of semantics, so that if a communication is well structured and accurately described it must therefore be more accessible. This practice may not be accurate to persons with mobility limitations. MML offers several conventions, of which it claims some are novel, for internationalization and accessibility to help it achieve its semantic objective.

MML claims to be presentation independent. A stated requirement of the specification is that the language does not imply any default presentation upon any of its elements. The intent is to allow software vendors more independent expressive freedom in how they use the language to publish content. Conventions for specifying stylesheets is provided to allow document authors to specify presentation over the defaults rendered by the software vendors. The specification specifies a convention for binding stylesheets to namespace declarations to prevent collusion between various competing stylesheets. The inventor claims this convention is a novelty.

Future Considerations

The inventor has previously mentioned that providing a standard method for describing and formatting content in email allows such access to the content in email by services. The inventor has stated that such a language would act as a universal API to email as a data service. No mention of how such an API could be used to provide data as a service to email has been stated publicly, however. The inventor has further stated in IETF mailing lists his belief that SMTP is a significantly more complicated transmission scheme than HTTP where that means everything that can possible exist across HTTP can just as easily exist over SMTP, but not the opposite[2]. The inventor has publicly stated his wishes to submit MML to the IETF standards body, but such has not yet occurred.


Personal tools

Served in 0.694 secs.