You can use the "OTP" feature CROSStrax offers, which is commonly known at 2 Factor Authentication. This will require users to enter a code they receive via email in order to log in.
To activeate this feature go to the left Navigation Bar and click on Settings.
In the Users & Security Section - Click on 2 Factor Password Authentication
Select add next to OTP>enable OTP>and choose how long to want the code to be valid for.
You will also need to make sure that the OTP is enabled for each user in their profile.