Sandbox User Email Not Updating After Verification

Hi everyone,

I have a Salesforce sandbox where I need to have 3 different users using the same email address.

I’m facing an issue when trying to update the email addresses of these users.

For example, one user currently has:

sim.taylor@xyz.com.invalid

I changed it to:

testuat@xyz.com

After saving, Salesforce sends a verification email to the new email address. The user clicks the verification link and completes the verification successfully.

However, when I go back to the User record in Setup, the email address still shows:

sim.taylor@xyz.com.invalid

It seems like the email change is not being saved even though the user has successfully verified the new email address.

Has anyone experienced this issue in a Salesforce sandbox, particularly with the .invalid email addresses?

What is the correct process for updating the email address so that it remains as the new email after verification?

Also, is there any limitation or recommended approach for having multiple Salesforce users with the same email address in the same sandbox?

Thanks in advance!