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3.1.5.6.2.2 Last Writer Wins Algorithm

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The last writer wins algorithm uses the PidTagLastModificationTime ([MS-OXPROPS] section 2.765) property to determine the winning version of the folder or message, as specified in the following steps:

  1. The version with the most recent PidTagLastModificationTime wins.

  2. For messages, if the value of the PidTagLastModificationTime property is equal on both objects, the tie-breaking winner is determined by comparing byte-to-byte values of the NamespaceGuid field for XID structures, as specified in section 2.2.2.2, in the PidTagChangeKey properties (section 2.2.1.2.7). The message with the larger NamespaceGuid field wins. For folders, if the value of the PidTagLastModificationTime property is equal on both objects, the server version is kept.

  3. If the byte-to-byte comparison in step 2 determines that the NamespaceGuid fields are equal, the version being imported wins.

The last writer wins algorithm MUST be used for conflicts detected during hierarchy synchronization and content synchronization operations on normal messages (unless the RESOLVE_NO_CONFLICT_NOTIFICATION flag is set in the PidTagResolveMethod property (section 2.2.1.4.1) set on the folder) as well as FAI messages, and folders.