Both in the mobile and desktop clients there is a “forget password” link on the Log in screen. The link is pointing to the VUP URL for example https://yourdomain.com/vup/resetpassword
The page shows a form where a user should enter his username or phone number. The system will then send an email containing a link with a token to the email address associated with the account.
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Once a user clicks on the link in email a browser will open the ChangePassword page with the token as a parameter. A form will appear where a user can set a new password.