Outlook on iPad and iPhone will not send emails

Follow these steps on both iPad and iPhone, in order:

1. Check internet connectivity
   Make sure the devices can reach websites like microsoft.com or bing.com in a browser. If they cannot, fix the network first. Fix network connection issues in Windows describes general connectivity checks that also apply conceptually to other devices.
2. Check for Outlook mobile sync issues
   If Outlook.com or Microsoft 365 mailboxes are used, there may be a sync problem between the mailbox and the mobile devices. Remove and recreate the device partnership:
   • In a browser, sign in to Outlook.com.
   • Go to Settings > General > Mobile devices.
   • Select each affected device and delete the device partnership, then Save.
   • Power off the iPad/iPhone completely, turn it back on, then open Outlook and let it resync.
     Detailed steps are in Fix email sync issues by removing a device from your Outlook mailbox.
3. Reset the account in the Outlook mobile app
   In Outlook for iOS:
   • Open Outlook > Settings.
   • Tap the account that is not sending/syncing.
   • Tap Reset Account and test sending mail.
4. Remove and re-add the account in Outlook for iOS
   If reset does not help:
   • In Outlook > Settings, tap the affected account.
   • Tap Delete Account > Delete From This Device.
   • Add the account again using the appropriate option (Outlook.com, Microsoft 365, Exchange, etc.).
     If prompted to configure as IMAP and calendar/contacts are needed, obtain the correct server settings from the email provider as described in server settings from your provider.
5. Verify that Outlook.com / Microsoft 365 storage is not full (if applicable)
   For Outlook.com accounts, if Microsoft cloud storage is full, sending and receiving email is blocked. Check mailbox storage using the storage link mentioned in Fix email sync issues by removing a device from your Outlook mailbox and free space if needed.
6. Check for known Outlook mobile issues
   If the app is crashing or behaving abnormally on iOS, follow the guidance in Troubleshoot Outlook mobile issues:
   • Ensure the device meets app requirements and has enough storage.
   • If the app crashes, clear the device browser cache, then remove and reinstall Outlook.

If these steps do not resolve the issue and Outlook on PC continues to work, contact Microsoft support for Outlook.com or Microsoft 365, or the mail provider’s support, with details that Outlook mobile on iOS cannot send while desktop Outlook works.

References:

• Fix email sync issues by removing a device from your Outlook mailbox
• Troubleshoot Outlook mobile issues
• Can't sync calendar and contacts with my phone or tablet
• I can't send or receive messages in Outlook