When you receive an email from and external organisation (not part of warminsterschool.org.uk)  Outlook now shows that it is an external email by showing the Word External in front of the From field in your inbox as shown below

This is so you can tell if someone is trying the pretend to be a member of staff or spoof a member of staff from an external email address.

To expand upon this when you open that email you will see in the header field the following (underlined in red)

This should help you identify spoofed emails but please also be aware that if someone email account has been compromised  this mitigation will not help. You must still think "Is that email correct are they asking me to do something out of the ordinary you can check by calling/speaking to the person first.