The Get-FailedContentIndexDocuments cmdlet returns a list of documents that couldn't be indexed. The most common reason is that there was no filter available for that document type or there was an attachment within the document. For example, the PDF filter isn't available by default. If an email message contains a PDF document, because there is no PDF filter, the document is marked as failed content indexing. After a new filter is installed, only new messages with attachments of the type for which the filter is installed are indexed. If you want to index older messages for the document type, the mailbox has to be moved. The cmdlet output provides details about items in a mailbox that couldn't be indexed, including an error code and the reason for failure. You need to be assigned permissions before you can run this cmdlet. Although this topic lists all parameters for the cmdlet, you may not have access to some parameters if they're not included in the permissions assigned to you. To find the permissions required…