A server-side rule has "[Kind] is [Meeting Request]" as an available type of rule filter, but client-side rules do not have the [Kind] filter at all.
Is there an email header that I could use to trigger a client-side rule to mimic that behavior?
A server-side rule has "[Kind] is [Meeting Request]" as an available type of rule filter, but client-side rules do not have the [Kind] filter at all.
Is there an email header that I could use to trigger a client-side rule to mimic that behavior?
If I understand your question correctly, you can use the Rules Wizard to create a rule which identifies any item "which is a meeting invitation or update". (This option is near the very bottom of the list; you might have to scroll down.)

For Mac Outlook 2011 I use the following client side rule for meeting requests:
Specific Header > Content-Class > Contains > calendarmessage
Better late than never :)