It depends on which kind of account(s) do you have on Outlook. If they are Outlook.com/Hotmail you don't need anything else, just add the account as Exchange on the One or download the Outlook app from the Play Store. The same for Yahoo! mail.
If the account is from work or third-party/unknown service, you can sync them using SnapPea, Moborobo or Mobogenie. SnapPea was the mos complete and its interface was better than the others. Try them. They work well and can also back up or sync other things like sms, music, apps, etc.