This morning I noticed that my phone drained more than 30% overnight with no usage. I checked the battery usage and found that my Mail App was causing 70% of my battery usage. This has never been the case and my settings haven't changed since I got my iPhone 6 in September. I have my phone set to check every 15 minutes, same settings I've used for years. I've rebooted the phone, but it has still drained 10% of my battery in a little over an hour. These are the same settings as my iPad, but I don't seem to have the draining problem on that device. Any suggestions?