#Find mailboxes that are larger than 100GB (for migrating to exchange online)
Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics | Where-Object {
    [int64]($_.TotalItemSize.Value.ToBytes()) -gt 100GB
} | Select DisplayName, @{Name="SizeGB";Expression={"{0:N2}" -f ($_.TotalItemSize.Value.ToBytes()/1GB)}}