Exchange W3WP Memory usage for MSExchangePowerShellAppPool and MSExchangeECPAppPool

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...

Four things come to mind when store.exe is seeing high usage.

1. Third-party applications on the Exchange server. It could be anti-virus (that's usually the case) that checks the mailbox database. Perhaps some form of special indexing or archiving tool. If you have non of those, move on.
2. The Exchange server itself has a virus. This happens sometimes. Sad, but true. To me, it seems that SBS machines are more prone to this, not because of anything about SBS itself, but more because of the culture surrounding the small deployment scenarious that SBS usually fits in.
3. The mailbox databases are experiencing some form of corruption that isn't enough to take the database offline completely. You need to research the "Information Store Integrity Checker (ISinteg)". If you have SP1 of Exchange 2010, ISinteg is no longer a standalone app, but has been turned into the followin two PowerShell / EMS cmdlets: New-MailboxRepairRequest and New-PublicFolderDatabaseRepairRequest
4. The Exchange server needs to be updated. I know, this one is kinda lame. However, plenty of update rollups, hotfixes and patches have been released that address spiking store.exe issues. Make double sure that you have all pertinent patches. Double check WSUS or whatever you use to manage patches. Make sure everything is approved and then wait to make sure that wuau.exe presents the updates to the SBS machine itself.