What determines the base of users searched when I type a name in the "Enter a name or email address" field in the "Send Link" box when sharing an Office document? My issue is that it pulls up too many users from my 150,000-count university (most of them students). I'd prefer that full-time employees show up in the suggested list before students. I do see that it appears to remember who I chose before so they rise to the top the next time. I hope that "recently-used" feature stays through different products and across time.
The list is basically all valid security principals with email addresses in your organization, it's taken directly from the server. There is no way to sort it based on employee type or any other criteria, it's not really intended to be browser (the assumption is that you *know* who you want to share with, thus users you've shared files with recently are bumped on top).