| Event Id | 9586 |
| Source | MSExchangeIS Mailbox |
| Description | A problem occurred while doing OST sync operation for user username. The message last attempted to sync was: Parent folder name: Inbox; FID: d-1922D; Message subject: Administrator; MID: 1-84A722; Error code: 0x50b. |
| Event Information | According to Microsoft: Exchange supports both Online and Offline client connection modes. In Online mode, the client is connected directly to the Exchange computers information store database, and all of the changes that the client makes are immediately written to that database. In Offline mode, changes that the client makes are stored in the offline folder files (.ost file) on the client workstation. When the client next connects to the server, the changes are synchronized between the offline and online information stores. The .ost file is similar to a personal folders (.pst) file, but the .ost file is automatically encrypted. The encryption key is stored in two places: in the mailbox on the Exchange computer and in a local Messaging Application Programming Interface (MAPI) profile that is configured on the client workstation. If the key is lost from both locations, the .ost file is unreadable. When a client connects in Online mode, the key in the profile is checked against the key in the information store database. If the keys differ, the client copy of the key is overwritten with the key from the information store, and a new .ost file is automatically generated on the client workstation. When you reset an information store database, a new offline key is generated in each new mailbox; therefore, the current .ost file becomes unreadable at the beginning of the first successful online connection. Any changes that are made before the synchronization of the current .ost file are not uploaded. |
| Reference Links | XCLN: OST and PST Quick Reference Considerations and best practices when resetting an Exchange mailbox database |
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