I have Windows Live Mail receiving e-mail from a POP3 server. A few times over the past years I have had all of my e-mails re-download from the POP3 server creating duplicates in Windows Live Mail. Removing e-mails from the server is not an option for business reasons (I run a small business and need to be able to access previous e-mails from anywhere using my e-mail provider's webmail service in case of emergency).  My account is listed only one time in Windows Live Mail.

In the past I was able to remove duplicate e-mails within Windows Live Mail/Outlook Express easily. I can't figure out how to do it now. I currently have 3 copies of every e-mail I received before July 8th in Windows Live Mail and only one of e-mails received since then. How do I remove the two duplicates of every e-mail from before July 8th?

Live mail is version 2011 (Build 15.4.3555.0308).