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. 

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You will also need to make sure that the OTP is enabled for each user in their profile. 

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Thank you,