Move archive mailboxes from a selected mailbox database to other databases

Move-ArchiveMailboxes.ps1

# fetch archive mailboxes from database
$database = 'MBDB1925'
$mbx =Get-Mailbox -Database $database -Archive | ?{$_.ArchiveDatabase.Name -eq $database}

# some variable
$file = ('e:\Temp\{0}ArchiveUsers.csv' -f $database)
$batchName = ('{0}-Archive-Offboarding' -f $database)

# prepare batch user CSV file
$mbx | Select-Object -Property @{Name = 'EmailAddress'; Expression = {$_.PrimarySMTPAddress}} | Export-Csv -Path $file -Encoding UTF8 -NoTypeInformation

# create migration batch
# change archive target database(s) to your needs
# the example distributes archive mailboxes across three databases 
New-MigrationBatch -Name $batchName -CSVData ([System.IO.File]::ReadAllBytes($file)) -Local -TargetArchiveDatabases ARDB1901,ARDB1902,ARDB1903 -AutoStart -NotificationEmails [email protected] -ArchiveOnly