Sign in to Outlook.com in a web browser, check mailbox storage first, and then send a fresh test message from another email account to determine whether mail is being rejected, redirected, or only failing to synchronize in an app.
1. Check whether the mailbox is full
In Outlook.com:
- Select Settings (gear icon).
- Open General > Storage.
- If storage is full or near its limit, save any important messages or download important attachments before deleting anything.
- Delete unneeded large messages and attachments, then empty Deleted Items to reclaim space.
- Wait several minutes and send a new test email from another account.
When Microsoft cloud storage is full, Outlook.com cannot receive mail. Messages sent while it was full are bounced to the sender and cannot be recovered later.^1^
Warning: Permanently emptied messages may be unrecoverable, so save anything important first.
2. Look for mail being hidden or redirected
If storage has available space:
- Check Junk Email, Deleted Items, and the Other tab.
- In the message list, select Filter > Sort > Date so the newest messages appear correctly.
- Open Settings > Mail > Rules and disable any unexpected rule that moves or deletes incoming messages.
- Open Settings > Mail > Forwarding and disable forwarding unless you intentionally use it.
- Review Settings > Mail > Junk email for accidentally blocked senders.^1^
Ask the test sender whether they received a non-delivery or “bounce” message. Its error text can identify whether the mailbox rejected the message.
3. Compare the web mailbox with the Outlook app
- Test message appears on Outlook.com but not in the app: delivery is working, and the problem is with that app’s synchronization.
- Test message does not appear on Outlook.com: the message did not reach the mailbox or was redirected by a mailbox setting.^2^
For an app-only problem, provide the device, Outlook version, and whether the account is Outlook.com/Hotmail, Microsoft 365 work or school, IMAP, or POP before removing and re-adding it. Do not remove a POP account until confirming that important local mail is backed up or synchronized to the server.
If the account password was recently changed, update the saved password in every connected Outlook or third-party mail app. Microsoft also notes that unusual sign-in activity can temporarily block an Outlook.com account.^1^
4. Check service status and request support
Check Microsoft’s public service-health page for an active Outlook incident.^3^
If no incident is listed and the fresh test message still does not reach Outlook.com:
- In Outlook.com, select Help on the menu bar.
- Enter cannot receive email.
- Complete the troubleshooter.
- Scroll to Still need help? and select Yes.^1^
For a work or school Microsoft 365 account, contact the organization’s administrator and ask for a message trace of the test email.^2^
References
- Can't send or receive email in Outlook.com | Microsoft Support
- I can send but i cannot receive new email - Microsoft Q&A
- Microsoft service health status