When migrating mailboxes to Exchange 2013, you can run into an error the regarding maximum number of bad items. This causes the import to fail:
Error code: -2146233088
This mailbox exceeded the maximum number of corrupted items that were specified for this move request.
The message exceeds the maximum allowed size for submission to the target mailbox.
A bad item can be one whose size is a bit large. The New-MailboxImportRequest commandlet can be called with the -BadItemLimit option, specifying a number of items> when using that option you must also specify the -AcceptLargeDataLoss option. For example, to import a mailbox called john.doe using a pst of john.doe.pst, the command would look as follows:
New-MailboxImportRequest -Mailbox john.doe -FilePath "\\myserver\E$\john.doe.pst" -BadItemLimit 1000000 -AcceptLargeDataLoss
If you have a number of mailboxes that have already failed, use the Get-MailboxImportRequest commandlet and pipe the items that match the Failed Status setting to a Set-MailboxImportRequest option defining a larger -BadItemLimit setting as follows:
Get-MailboxImportRequest -Status Failed | Set-MailboxImportRequest -BadItemLimit 1000000