This documentation is archived and is not being maintained.

PidLidCategories Canonical Property

This content is outdated and is no longer being maintained. It is provided as a courtesy for individuals who are still using these technologies. This page may contain URLs that were valid when originally published, but now link to sites or pages that no longer exist.

Specifies a list of categories for an item.

Associated properties:


Property set:


Long ID (LID):


Data type:




To generate a keywords header field, clients must set the value of this property to the desired values. This property has multiple strings; each category should be mapped to a single keyword.

Multipurpose Internet Mail Extensions (MIME) writers should copy each sub-value of this property to a separate keyword in the Keywords header field, with a comma (U+002C) and space (U+0020) separating each keyword. MIME writers may drop this property instead of copying it to the keywords header field, in order to avoid conflict among different sets of categories in different organizations.

Protocol Specifications


Provides property set definition and references to related Exchange Server protocol specifications.


Converts from Internet standard e-mail conventions to message objects.

Header Files


Provides data type definitions.