The urn:schemas:httpmail: namespace, similar to the urn:schemas:mailheader: namespace, defines core properties for messages. However, within this namespace, string fields are returned with all characters that were encoded per RFC 1522 decoded into Unicode characters. This namespace also contains additional fields not found in urn:schemas:mailheader: that are routinely used to render messaging information to clients through a Web browser or user agent. The following properties have counterparts in the urn:schemas:mailheader: namespace.
The following properties identify the Uniform Resource Identifiers (URIs) to a particular user's mailbox folders, and the Microsoft® Exchange mail transmission URI:
msgfolderroot Field (root mailbox folder)
sendmsg Field (Exchange mail transmission Uniform Resource Identifier (URI))
Use these fields to render messaging information within Web browsers or user agents (UAs), especially when characters within the various message headers are not US-ASCII, or when you are unsure what character sets to expect. All fields within the urn:schemas:mailheader: namespace are always returned as US-ASCII characters, with any non-US-ASCII characters encoded using the mechanism described in RFC 1522.