Outlook is extremely slow and not showing emails

Since the issue happens on both the iPhone and the laptop, first check whether this is a service issue rather than a device issue.

1. If this is a Microsoft 365 work or school account, have a Microsoft 365 admin sign in to the Microsoft 365 portal and check Service health for any Exchange Online or Outlook-related incident.
2. If email works on a computer and there is no outage, the problem is likely with the mobile app or iOS Mail app rather than the mailbox itself.
3. On iPhone/iPad, if the problem is in the default Mail app and prompts such as “Please enter the password for the Outlook account”, “Account not authenticated”, or “Cannot Get Mail – The connection to the server failed” appear, re-enter the account password:
   • Open Settings
   • Tap Mail
   • Tap Accounts
   • Select the Outlook account
   • Tap Account Settings or the Password field
   • Enter the correct password
   • Tap Done
   • Open Mail again and confirm mail is syncing and sending/receiving
4. If sign-in errors appear while re-adding or authenticating the account, recover account access first using the matching Microsoft support flow for errors such as:
   • “That password is incorrect for your Microsoft account.”
   • “We can't sign you in”
   • verification code errors
5. If Outlook mobile is crashing on iPhone or iPad, close the app, restart the device, update Outlook from the App Store, then go to Settings > General > iPhone Storage > Outlook > Offload App, and reopen it.
6. If Outlook is also very slow on desktop, local network issues can also cause this, including proxy, firewall, or Internet provider issues.

If the mailbox is unavailable on both iPhone and laptop at the same time, the fastest path is to verify service health first. If there is no outage, then focus on re-authenticating the iPhone account and checking whether the issue is specific to the app being used.

References:

• Outlook performance is slow in the Microsoft 365 environment
• iOS & iPadOS users may experience issues accessing their Outlook and Hotmail accounts from the iOS/iPadOS default Mail app | Microsoft Support
• Troubleshoot Outlook mobile issues | Microsoft Support