You don´t know why the PIN isn´t requested immediately, but only after a certain period.
Setting "Request Pin to" not set up as "manual"
The PIN request can be changed in the General Settings of GMX Mail App for Android geändert werden.
Set up the PIN-request
Tap the menu symbol in the menu bar.
The menu navigation is shown.
Tap the gearwheel symbol.
Tap General settings.
Under Data protection, tap PIN code required.
Enter a 4-digit PIN and confirm it.
If you wish to change your PIN, you must first enter the original PIN for unlocking before choosing a new PIN.
If your Android smartphone has a fingerprint sensor,
you have the option of activating fingerprint access protection alternatively to the PIN, in order to activate the device
simply without using a password.
Fingerprint access protection must be set in the device settings.
You can determine the intervals at which the PIN is queried. Choose between one minute, 5 / 10 / 15 / 30 minutes or set the
PIN request to Manual only,
, to request the PIN only after you have locked the app manually by tapping on Lock app in the side menu