outlook not delivering emails

Question

Third party emails being delivred to the server. However, outlook not delivering emails. Occassionally i can send emails out from the outlook on my HP desk top. Same situation on two differnt computers.

Incoming mail set up properly but mail not being delivered in outlook. Mail from third part arrives on iphone without any issues and on time.

Answer 1

Hi Alfred Dinicola, 

I hope you are doing well ! I just want to check if you have had a chance to test the steps earlier? Please let me know if they helped resolve the issue or if you are still experiencing any difficulties. I am here to assist you further.

Best Regards

Answer 2

Dear Alfred Dinicola, 

Thank you for reaching out to the Microsoft Q&A forum. I understand email is reaching your mailbox, but New Outlook for Windows is not showing incoming mail reliably and sending only works occasionally, and you see the same behavior on two different PCs. I’m sorry for the disruption. Is the affected mailbox an Outlook.com/Hotmail/Live/MSN account, or a third‑party email address added into new Outlook—and does the same missing mail happen on the web for that same mailbox? 

• Verify whether this is an Outlook.com/Hotmail mailbox vs a third‑party mailbox added into new Outlook 
  • Please confirm: 
  • Does the missing mail also appear (or not appear) when you sign in to Outlook on the web for the same mailbox? 
  • What is the email domain (Outlook.com/Hotmail/Live/MSN vs a third‑party domain)? 
• If this is an Outlook.com mailbox: check Microsoft storage/quota first 
  • If Microsoft cloud storage is full, you cannot send or receive in Outlook.com (and mail sent while full can bounce). This can look like “mail not delivering” on PC even when another device still shows older cached mail. Check Storage in Outlook.com and clear space if needed.  
• Rebuild the new Outlook connection by removing and re-adding the account 
  • For new Outlook allows removing the account from the app, then adding it back.  
  • Reset the new Outlook app itself. Restart the app via Task Manager and, if needed, uninstall and reinstall new Outlook for Windows.  

Look forward to hearing from you. Have a nice day!

Answer 3

Follow these steps to troubleshoot Outlook not delivering mail while messages arrive correctly on other devices:

1. Confirm internet connectivity
   • On each Windows PC, open a browser and verify that sites such as microsoft.com or bing.com load correctly. If they do not, fix the network connection first.
2. Check for sync issues in Outlook
   • In New Outlook for Windows, go to the View tab and use the Sync button (if available) to force a manual sync. Watch the status bar at the bottom for any sync error messages.
   • If sync errors appear, follow any prompts or error details shown there.
3. Verify Outlook is actually sending
   • After sending a test message, check:
     • Outbox: If messages remain here, Outlook is not completing send.
     • Sent Items: If messages appear here but never reach recipients, the problem is likely on the server or with delivery, not Outlook itself.
4. Use Microsoft’s Outlook troubleshooters
   • Run the Classic Outlook troubleshooters for send/receive issues as described in the “Issues sending and receiving email” article. These tools can detect profile problems, version mismatches, or configuration issues that prevent sending.
5. Check for damaged send/receive configuration (Classic Outlook)
   • If Classic Outlook is used on either PC and messages are not sent automatically, recreate the Send/Receive group:
     • Outlook 2010 or later: File → Options → Advanced → Send/Receive → select the group → Copy → name the new group → select the old group and clear Include this group in Send/Receive (F9) for both Online and Offline → Close → restart Outlook.
6. Compare account configuration with working device
   • On the iPhone (where mail works), note the exact server type (Exchange, IMAP, POP) and server names.
   • On each PC, open Outlook account settings and confirm the same account type and server details are used, and that authentication settings match.
7. If messages are bouncing (NDRs)
   • If any sent messages generate “delivery failed” or “undeliverable” reports, review the error text:
     • If the error mentions mailbox full, invalid address, or message too large, follow the specific guidance in the “Sent email in Outlook.com comes back ‘delivery failed’” article (for example, reduce attachment size or correct recipient address).
8. If problems persist on multiple PCs
   • Because the same issue occurs on two different computers, focus on:
     • The mail profile (remove and re-add the account in Outlook).
     • Running the Outlook troubleshooters.
     • Testing via the web interface for the same mailbox to confirm whether the server is sending correctly.

If, after these steps, Outlook still does not deliver messages while the same account works on iPhone, use the Outlook troubleshooters and then contact support as indicated in the “Issues sending and receiving email” article for deeper investigation of the account or service.

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References:

• I can't send or receive messages in Outlook
• Issues sending and receiving email
• E-mail messages are not automatically sent or received at startup in Outlook
• Sent email in Outlook.com comes back "delivery failed"