1.3.3 Property ID Ranges

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The 65,536 possible values of the property ID are divided into sub-ranges reserved for various purposes, as described in the following table.

In this context, the term "non-transmittable" refers specifically to transmission via an email transport protocol (such as SMTP), and not to any network transport protocol (such as TCP):

  • Servers do not allow property IDs in ranges specified as non-transmittable to be submitted for transport to another server via an email transport protocol. Property IDs in ranges not specified as non-transmittable are submitted for transport to another server.

  • Clients can use properties in ranges described as message class-defined for application-defined purposes. When doing so, applications specify a value for the PidTagMessageClass property (section 2.788) that is distinct from any value listed in section 1.3.1.

  • Clients can use any named property for application-defined purposes. No constraint is placed on the value of the PidTagMessageClass property in this case, but the property set of the named property is distinct from any value listed in section 1.3.2. Note that named properties are transmittable.

  • Clients can use properties in ranges specified as transport-defined, but they cannot define new properties in those ranges.

  • Clients can use and define properties in ranges specified as user-defined, but need to avoid conflicts with alternate definitions of the same property ID.

    Range minimum

    Range maximum

    Description

    0x0001

    0x0BFF

    Message object envelope property; reserved

    0x0C00

    0x0DFF

    Recipient property; reserved

    0x0E00

    0x0FFF

    Non-transmittable Message property; reserved

    0x1000

    0x2FFF

    Message content property; reserved

    0x3000

    0x33FF

    Multi-purpose property that can appear on all or most objects; reserved

    0x3400

    0x35FF

    Message store property; reserved

    0x3600

    0x36FF

    Folder and address book container property; reserved

    0x3700

    0x38FF

    Attachment property; reserved

    0x3900

    0x39FF

    Address Book object property; reserved

    0x3A00

    0x3BFF

    Mail user object property; reserved

    0x3C00

    0x3CFF

    Distribution list property; reserved

    0x3D00

    0x3DFF

    Profile section property; reserved

    0x3E00

    0x3EFF

    Status object property; reserved

    0x4000

    0x57FF

    Transport-defined envelope property

    0x5800

    0x5FFF

    Transport-defined recipient property

    0x6000

    0x65FF

    User-defined non-transmittable property

    0x6600

    0x67FF

    Provider-defined internal non-transmittable property

    0x6800

    0x7BFF

    Message class-defined content property

    0x7C00

    0x7FFF

    Message class-defined non-transmittable property

    0x8000

    0xFFFF

    Reserved for mapping to named properties. The exceptions to this rule are some of the address book tagged properties (those with names beginning with PIDTagAddressBook). Many are static property IDs but are in this range.