Hi,
Starting with Android 6.0 a Doze mode feature was included which optimizes memory and battery life by restricting app background usage when the device is not in use. Aqua Mail will notify you within Settings > Mail, receiving if it is not allowed to update your e-mail in the background.
You can also adjust which apps are affected by Doze mode in your device settings:
- On Samsung phones go to Settings > Device Maintenance > Battery. You’ll want the “Power saving mode” to be OFF. Under App power monitor, find Aqua Mail and change it's status to "unonitored apps".
- On Xiaomi phones go to Settings > Additional Settings > Battery & Performance > Manage apps battery usage > Whitelist Aqua Mail
- On Huawei phones go to Settings > Advanced Settings > Battery manager -> Protected apps -> Set Aqua Mail as Protected
- On ASUS phones go to the Mobile manager app > Auto-start manager > Allow for Aqua Mail