how do I sync my outlook to my iphone?

If Outlook on iPhone was working before and now messages are no longer arriving, use this sequence:

1. Check whether Outlook.com has a service issue.
   • For Outlook.com, first check the server status of Outlook.com.
2. Reset the account in the Outlook app.
   • In Outlook on iPhone, go to Settings.
   • Tap the account that is not syncing.
   • Tap Reset Account.
   • Check whether mail starts syncing again.
3. If reset does not help, remove and add the account again.
   • In Settings, tap the account that is not syncing.
   • Tap Delete Account > Delete From This Device.
   • Add the account again in Outlook for iOS.
4. If prompted to set up the account as IMAP, stop there.
   • IMAP and POP can sync email, but not calendar and contacts.
   • If server settings are requested, get the correct server settings from the email provider.
5. If mail still does not sync, remove the mobile device partnership and reconnect.
   • In Outlook.com on the web, go to Settings > General > Mobile devices.
   • Select the iPhone and delete the device partnership.
   • Select Save.
   • Power off the iPhone completely.
   • Turn it back on and sync the mailbox again.
6. If the issue is only in the app and mail works on a computer, use in-app support.
   • In Outlook for iOS, open in-app support and choose Contact Support.

References:

• Can't sync calendar and contacts with my phone or tablet
• Set up the Outlook app for iOS
• Fix email sync issues by removing a device from your Outlook mailbox
• Troubleshoot Outlook mobile issues