Sometimes you need to manually download the Offline Addressbook (OAB) for the Outlook email client.
When initiating a manual OAB download, you might encounter a 0x80200051 error. A common mitigation scenario is to switch between Outlook Online Mode and Outlook Cached Mode multiple times. This mitigation scenario does not solve the issue.
When you active Outlook Cached Mode, a full OAB download is required. The OAB download dialogue provides an option to download OAB changes only. This option is selected by default. To start a full OAB download, you must deselect the checkbox.
You will not encounter the mentioned error using this download setting, and the Offline Addressbook will be downloaded by your Outlook email client successfully.