I noticed my outlook email accounts wouldn't sync at all until I restarted my phone. My school's email was still synced and also using Microsoft Outlook ( or exchange?) services. Is this just me or a known issue?
There was an issue reported with 10.0.1 on various forums. I had this on an iPad Air 2. Fix was to remove the account in Mail Settings and then add it back. After that it took 5 minutes, but has been syncing fine since then.