Circumvent Outlook Rules in Exchange 2010

We just completed an Exchange 2007 migration this past weekend. After each migration we review what worked and what didn't. One of the problems we faced - clients setup delegate forwarding rules, so the "bosses" and their delegates had copies of the meeting invites in their inboxes. The client used Redemption to write a MAPI script to disable those rules, but it didn't work as planned. The good news-- the Sumatra process correctly built the bosses calendars! The bad news - delegate had a bunch of meeting requests in their inbox that they had to delete (Not a show stopper -- just tedious!)

Had they migrated to Exchange 2010, this would not have been necessary because Exchange 2010 allows you to manage rules using these six commandlets: Get-InboxRule, Set-InboxRule, Remove-InboxRule, Disable-InboxRule, Enable-InboxRule and New-InboxRule.

One approach is to use "Get-InboxRule" to find all enabled, server-side rules. Disable those rules (remember which rules you disabled so you can re-enable them after the migration.)

We came up with another approach: Add a new rule that has the "highest" priority, have that rule do nothing, then say "stop processing rules." After the migration, remove that rule.

Here's how we approached it for one user, say, Zyg:

• New-inboxrule -mailbox:zyg@mailbox.sumatra.com -name:"_sumatraHiPriorityRule" -Priority "0" -StopprocessingRules:$true -Confirm:$false

and then to remove:
• Remove-inboxrule -mailbox zyg@cod.sumatra.local -Identity:"_sumatraHiPriorityRule" -Confirm:$False

Caveats:

• Note the priority zero (0) makes this rule the highest-priority rule. All others drop down one.
• We are ignoring the power-rule-user scenario: the user exceeds Exchange's inbox rule memory size buffer limit (it's 32KB) (or about 40-50 rules.) Obviously when you're at the limit you can't add any more rules. We don't have a suggestion except to say "look" for disabled rules and ask the end user if a few could be removed.
• The "-force" parameter - removes disabled rules AND all Outlook client-side rules.
• new-InboxRules doesn't accept pipelined userlist from "get-mailbox -filter {isResource -eq $false}". What happens if you have 5,000 accounts? Stay tuned ---