PidTagMessageSize Canonical Property

Applies to: Outlook 2013 | Outlook 2016

Contains the sum, in bytes, of the sizes of all properties on a message object.

Associated properties:
Data type:
General messaging


It is recommended that message objects expose this property. The message size indicates the approximate number of bytes that are transferred when the message is moved from one message store to another. Being the sum of the sizes of all properties on the message object, it is usually considerably greater than the message text alone.

Most message store providers compute this property for messages that they handle. However, some message store providers do not support this property. In any case, this property is not available until the IMAPIProp::SaveChanges or IMessage::SubmitMessage method has been called.

Protocol specifications


Provides references to related Exchange Server protocol specifications.


Handles message and attachment objects.


Handles folder operations.


Specifies permissible operations for the core message store objects.

Header files


Provides data type definitions.


Contains definitions of properties listed as alternate names.

See also

MAPI Properties

MAPI Canonical Properties

Mapping Canonical Property Names to MAPI Names

Mapping MAPI Names to Canonical Property Names