How-to redirect mail to someone else than the intended recipient

Issue:

I want to have external emails coming in to userX@domain.com go to userY@domain.com.  Can this be done in proofpoint?

Answer:

No.  Assuming you're on Office365 (80%+ of our clients are), you need to do that in office365 with a mail flow rule.

Solution:

Go to your exchange admin

-> Mail Flow

---> RULES

Create a new rule as per below: