How to create Exchange server rules for all users

Once you create the Distribution Group, go into AD Users and Computers and edit the properties for the group. On the Security tab, add one or more users you wish to grant "Send As" permissions to, then select the "Send As" permission. You cannot do the through the EMC or EMS as far as I know.

The first error is because PowerShell implicit remoting doesn't support a piped ForEach. You would have to assign to a variable then do ForEach In like:

$MBs = Get-Mailbox -OrganizationalUnit "supernova.local/Active Users" -ResultSize Unlimited

ForEach($MB in $MBs)
{
New-InboxRule -Name "Spam Move" -Mailbox $MB -MoveToFolder "kerry:\Junk E-Mail" `
-SubjectContainsWords "[Spam:" -StopProcessingRules $true -Confirm:$false -Force
}

The second issue I see is that you are specifying -Mailbox on in the command, but that should be coming from the pipeline. In the above example since it's in ForEach reference the iteration variable $MB instead. I'm guessing the folder ID you're specifying in -MoveToFolder would also have to be different, perhaps something like $($MB.SamAccountName):\Junk E-Mail`. You may have to tinker with some of this.

Please bear in mind I came across this thread because I'm having my own troubles with New-InboxRule, so it may still not work. Because of these other issues I'm not able to test this. That said everything I've pointed out here is general syntax, and should hold true regardless.

Let me know how it goes...