Outlook 365 desktop stops sending email on new computer

Copper Contributor

I recently purchased a new desktop computer and installed office 365. After setting my email in the outlook desktop app I found that I cannot send email from outlook. I have been getting a 0x80040115 error. I have tried the following: 

       Factory reset of new computer 

       Repair of office - both ways

       Updated windows 11

       Deleted and re added email accounts (this actually helps initially but after a few days it stops working)

       Disabled virus software and firewall 

       Restarted many times

       Reduced size of mailbox 

       Deleted app data (again helps for short time)


This will also effect corporate email after several days.  I have no issues sending email from same account from my phone, laptop, or web mail. 


I'd appreciate any thoughts,





1 Reply




The Outlook error 0x80040115 occurs when a user tries to send an email, but the Outlook application fails to synchronize the changes to the mailbox server.


The error 0x80040115 specifies that your Outlook is unable to connect to the server. However, below given are the most common reason for this error occurrence.


  • corrupted DNS cache
  • Large Offline Cache (OST)
  • Incompatible or Third-party Add-Ins
  • Incorrect Outlook Installation


If you are facing the above Outlook error, you can follow the following methods to fix the issue.


Flush DNS Cache:


Flushing the DNS cache will clear your DNS cache, as the issue might be due to DNS configuration.


  • Firstly, open the Start menu by pressing Win + X keys.
  • Then, type the command prompt and open it with Admin rights
  • Next, type the below command and press Enter,

ipconfig /flushdns

  • Lastly, restart Outlook and try once by sending an email.


Disable Add-Ins:


Third-party add-ins installed in Outlook can cause an issue with sending or receiving emails. You can try to launch Outlook in safe mode to see if that fixes the issue,


  • Firstly, press Windows + R Keys to open a Run dialog box.
  • Type in the following and hit Enter:

Outlook /safe

  • Once Outlook opens in safe mode, try to send an email and check if the issue persists.
  • Now, If the issue gets fixed, you must remove the add-ins by going to File and then Options.
  • Then, disable the add-ins that won't start with Microsoft.
  • Next, on the left-side pane, click Add-ins and remove all the third-party add-ins.
  • Lastly, close the dialog and restart Outlook.


Repair corrupt OST file:


Outlook stores a local copy of your emails in an OST file. When an OST file gets corrupted, you won't be able to receive or send any new emails.


  • Firstly, close Outlook and navigate to the following path,

C:\Program Files\Microsoft Office\root\Officexx 

  • Then, locate and launch the SCANPST tool.
  • Next, click Browse, select the OST file and click Start.

This tool will scan the OST file for errors. If it finds an issue with your OST file, you will get the option to repair it.

  • Lastly, after repair, start Outlook and check if the issue is addressed.


Thus, I hope the methods above can help you fix the Outlook 0x80040115 error and can send emails from Outlook.