PidTagAttachLongPathname Canonical Property
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PidTagAttachLongPathname Canonical Property

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Contains an attachment's fully-qualified long path and filename.

Associated properties:




Data type:



Message attachment

These properties are applicable when you use any of the PR_ATTACH_METHOD (PidTagAttachMethod) property's values that indicate attachment by reference: ATTACH_BY_REFERENCE, ATTACH_BY_REF_RESOLVE, or ATTACH_BY_REF_ONLY. Platforms that support long filenames should set both PR_ATTACH_LONG_PATHNAME or associated properties and PR_ATTACH_PATHNAME (PidTagAttachPathname) properties when sending, and should check PR_ATTACH_LONG_PATHNAME or associated properties first when receiving.

The client application should set these properties to a suggested long path and filename to be used if the host machine receiving a message supports long filenames. Setting these properties indicates that the attachment data is not included with the message but is available on a common file server.

Unlike the directories and filenames provided by PR_ATTACH_PATHNAME, these directories and filenames are not restricted to an eight-character directory or filename plus three-character extension. Instead, each directory or filename can be up to 256 characters long, including the name, extension, and separator period. However, the overall path is limited to 256 characters.

Clients should use a universal naming convention (UNC) in most cases when the file is shared, and should use an absolute path when the file is local.

MAPI works only with paths and filenames in the ANSI character set. Client applications that use paths and filenames in an OEM character set must convert them to ANSI before calling MAPI.

Protocol Specifications


Handles message and attachment objects.


Specifies the properties of rights-managed encoded messages.

Header Files


Provides data type definitions.


Contains definitions of properties listed as alternate names.

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