How do you block spoofed communications from HR, Payroll, the President...?

["John R. LaPrad" <jrl () SVSU EDU>]

Hello Colleagues, I am wondering what other universities are doing to
block emails to users that have spoofed official people or offices on
campus. Emails claiming to be from HR or Payroll, or the President.  Do
you have a way to 'guarantee' official communications so that end users
can easily distinguish between the real and the fake?
We have an Office 365 email environment and also have many third party
organizations that send mail, for our, as our, domain.
Any all thoughts are welcome

Thank you for your time

John LaPrad - CISSP, CIHE, GIAC/GMON
Information Systems Security Manager
Saginaw Valley State University
7400 Bay Rd. University Center, MI
Phone: 989-964-7134
jrl () svsu edu