This document outlines steps to take if you send a message from your @u.northwestern.edu, @nlaw.northwestern.edu, @alum.northwestern.edu, @kelloggalumni.northwestern.edu, or @fsm.northwestern.edu email account but the recipient never gets the message.
First, verify that you are sending your email to a correctly-spelled, active email address, and that the recipient is able to receive messages from other sources. If they still cannot receive the message, follow the troubleshooting steps at this Google support article.