13:48:16 ERROR: [4970-105-47-80004005] Unable to open mailbox for user 'USER@DOMAIN.COM'
13:48:16 ResolveNames(SMTP:USER@DOMAIN.com):
13:48:16 [80004005] Unspecified error
The above error may be seen when the profile selected on the Select Destination Exchange Server screen does not have Receive As permissions to the target mail stores.
Confirm the receive-as permissions are set correctly on the migration account.
Setting Receive-As permissions solutions:
To Set the Receive As Privilege in Exchange 2010 or 2007 (for all mail stores):
In PowerShell (for Exchange 2010) or Exchange Management Shell (for Exchange 2007), type this command:
get-mailboxdatabase | add-adpermissions -user <username> -extendedrights receive-as
Also, for Exchange 2010 (only): This AD admin account must be configured with remote PowerShell enabled,
by this Exchange Shell command:
Set-User <alias> -remotepowershellenabled $true
... where <alias> is the AD account to which you are granting access.
• To Set the Receive As Privilege in Office 365 (for all mail stores):
In Office 365 Management | Users | Settings, assign administrator permissions to the admin migration
account.
Also, for Office 365 (only): This AD account must be configured with Application Impersonation, by this PowerShell
cmdlet (in one continuous line):
New-ManagementRoleAssignment -Role "ApplicationImpersonation" –User <userid>
