When an iOS installation is registered with uppercase device token, it does not get removed when APNS marks the token as invalid. This is probably because on this line [1] the invalid tokens are converted to lowercase and then asked to be removed from datasource. Anyway the problem is that the token in datasource is saved in the uppercase format and thus does not get removed.

This might also affect other platforms, but I haven't test that.

1 - https://github.com/aerogear/aerogear-unifiedpush-server/blob/3c88fe34ba9874249fb2702e27f654c67df7f6d6/push/sender/src/main/java/org/jboss/aerogear/unifiedpush/message/sender/APNsPushNotificationSender.java#L119