Hi, recently Windows Live Mail didn't sync my hotmail(outlook) account any more, but my gmail account is fine. Then I found solution below and it starts sync back again. However, if I write an email from Window Live Mail, my sent emails creates double copies into my Sent folder in the both of Windows Live mail and outlookMail. On the other hands, if I write an email from outlook Mail, that's fine. 

Thus how do I fix this double copies of  sent emails?

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1. When viewing your message list, press Ctrl-Shift-T to start the Add your email accounts wizard.
2. Enter your email address, password and display name for outgoing messages.
3. Select Manually configure server settings and click Next.
4. For the incoming server, select IMAP from the dropdown.
   For the incoming server address, enter imap-mail.outlook.com and change the port number to 993.
   Select Requires a secure connection (SSL).
   For Authenticate using, select Clear text from the dropdown.
   For Log-on username, enter the full email address.
5. For the outgoing mail server address, enter smtp.live.com and change the port to 587.
   Select Requires a secure connection (SSL) and Requires authentication.
6. Click Next and Finish.
   
   

The program will try to connect and download the account folders and their contents. This may take some time if there are a lot of folders and/or messages, and it may stall. Be patient.
 

• If the program successfully downloads the account folders, right-click on the new account name in the folder pane and select Properties. On the IMAP tab,
   
  • Select Check for new messages in all folders and Store special folders on IMAP server;
  • Enter the following paths (carefully - if they are not exactly as shown, it may not work):
    Sent Items path: Sent
    Drafts path: Drafts
    Deleted Items path: Deleted
    Junk path: Junk