email problems

Test the account in Outlook.com on the web first, because failure on both the iPhone and computer usually requires resolving an account, storage, or service issue before repairing either app.

1. Test Outlook.com directly

1. Open a private or incognito browser window and sign in to Outlook.com.
2. Send a simple message to yourself:
   • No attachment
   • No signature
   • One recipient
3. Check Inbox, Other, and Junk Email for the message.
4. Note any displayed error or returned “delivery failed” message.

If sending and receiving also fail in the browser, continue with the account checks below. If webmail works, skip to Fix the iPhone and computer apps.

2. Check account-wide causes

1. Check Microsoft service health.
   Review the Service Health Status site linked from Microsoft’s Outlook.com known-issues page. If an active Outlook.com incident is listed, wait for Microsoft to resolve it before changing your devices.^1^
2. Check storage.
   In Outlook.com, open Settings → General → Storage. Delete unnecessary messages—especially messages with large attachments—and empty Deleted Items and Junk Email if storage is full. Microsoft cloud storage at capacity prevents both sending and receiving; messages rejected while storage was full cannot be recovered automatically.^2^
3. Check the account password or block.
   • If the password was recently changed, sign out and sign back in with the new password.
   • If Microsoft reports unusual activity or a temporary block, complete the displayed account-verification process.
   • If sign-in itself fails, use the Microsoft account sign-in helper linked from Microsoft’s troubleshooting page.^2^
4. Check whether incoming mail is being redirected.
   In Outlook.com, open Settings → Mail, then inspect:
   • Rules — disable any rule that deletes or moves incoming messages.
   • Forwarding — turn off unexpected forwarding.
   • Junk email — review blocked senders.
   Also select Filter → Sort → Date and check the Other tab so newer messages are not hidden by sorting or Focused Inbox.^2^
5. Inspect sending errors.
   If mail returns as “delivery failed,” retain the complete error message. Common causes include an invalid recipient, a full recipient mailbox, server problems, or spam filtering. Outlook.com also cannot send an attachment larger than 25 MB.^2^

3. Fix the iPhone and computer apps only if webmail works

Webmail working confirms that the mailbox itself can send and receive.

If the iPhone uses Outlook:

1. Open Outlook → profile/account icon → Settings.
2. Under General → Accounts, select the account.
3. Tap Reset Account, then restart Outlook.
4. If it still fails, remove and re-add the account. Outlook.com and Microsoft 365 accounts that previously synchronized can be repaired by removing the synchronization partnership and adding the account again.^3^

If the iPhone uses Apple Mail:

1. Open Settings → Apps → Mail → Mail Accounts.
2. Select the affected account and re-enter the current password if requested.
3. If necessary, delete and re-add it using Outlook.com as the account type—not a manually configured IMAP account.

Deleting an account from the iPhone removes its locally synchronized copy, so first verify that the messages are visible in Outlook.com.

On the computer: sign out of the Outlook application and sign back in with the current password. If webmail continues to work but the computer application does not, the remaining issue is specific to that application; record whether it is new Outlook, classic Outlook, Apple Mail, or another program before seeking support.

4. Escalate if Outlook.com itself still fails

While signed in to Outlook.com, select Help, enter the problem, and press Return. If the suggestions do not resolve it, scroll to Still need help? and select Yes. For Outlook on iPhone, open the account menu, tap ?, and select Contact Outlook Mobile Support.^4^

Include the exact error message, whether webmail can send the self-test, and whether the test message reaches Inbox, Other, or Junk.

References

1. Fixes or workarounds for recent issues on Outlook.com
2. Can't send or receive email in Outlook.com | Microsoft Support
3. Troubleshoot Outlook mobile issues | Microsoft Support
4. How to get support for Outlook.com | Microsoft Support