Specifically, it will detect if a University of Sheffield email address appears to have been spoofed from a non-Sheffield Uni server - that means if somebody has tried to make it look like the email that they have sent is actually coming from someone else.
When you receive an email like this, you'll see the message: 'Warning: Sender not verified' at the start of the email subject.
The trouble is, there are sometimes legitimate reasons why someone might send a message appearing to be from someone else. Event management websites such as Eventbrite might send automatic reminders about an event, with the email appearing to come from the event owner's address.
We don't know at this stage how many, if any, false positives there might be. If you do find a false positive in your inbox, then let our helpdesk know by forwarding it to email@example.com.