Office 365 Import job fails with MailboxAmbiguous error in the Import job log file
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Original KB number: 4025464
When you use the Office 365 Import Service in the Security & Compliance Center to import PST files through the network or drive shipping, you may receive an error message that resembles the following:
Test.pst,Test@constoso.com,Failed,MailboxAmbiguous,0,0,,0,Microsoft.Exchange.Configuration.Tasks.ManagementObjectAmbiguousException, The operation couldn't be performed because Test@constoso.com matches multiple entries, such as 'Test'
This issue occurs when you have objects that have the same user principal name (UPN) or Simple Mail Transfer Protocol (SMTP) address in Exchange Online.
To work around this issue, run the following commands to see whether the objects are recipients or soft-deleted users:
Get-Recipient <SMTP_ADDRESS> Get-Mailbox <SMTP_ADDRESS> -SoftDeletedMailbox Get-MailUser <SMTP_ADDRESS> -SoftDeletedMailUser
After you find the user, you can use the Exchange GUID as the target mailbox in mapping the CSV file.
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