If you would like to receive a one-time authentication code (mTAN) every time you log in, you can manage this during the login process.
When entering the one-time code sent to your phone, the option to remember the device is automatically selected. To ensure the device is not saved, you must unselect this option each time you log in. If the device is not saved, you will be required to verify every login using a one-time code and email confirmation, even when using the same device.
You can also remove any saved or recognised devices from your account. Once removed, you will be asked to re-authenticate the next time you log in.
For more information on how to view or manage your registered devices, please read How do I find my registered devices in Raisin UK?