If you are trying to organize your email to make it easier to process, you may want to consider trying a “non-Purdue” email rule. A non-Purdue email rule will automatically move any email message that does not come from an @purdue.edu address into a non-Purdue folder. You can add exceptions to the rule so certain non-Purdue email addresses that are a priority for you will remain in your primary Inbox folder. Here is a PDF document describing how to set this up:
https://edit.education.purdue.edu/download2/Outlook-NonPurdue-Rule.pdf
~ Bob