Sharing A Sheet Outside of Network


Good Afternoon,

I am trying to share a sheet with someone outside of my network (A project manager at another company). I am giving her "Viewer" permissions so she can check in on our projects. When I go to sent the share email, I get a popup that says another person owns her email account and it asks if I want to proceed with sharing to the other person's email ? Any clue why this happens, and if she is able to view the sheet still?