I have been using Windows Live Mail for some years. I addition to the standard folders I have created additional storage folders for the purpose of keeping emails from various persons I work with on genealogy research,  I have set up over 10 folders by surname where a large number of emails are stored that I have received over the years.  Very vital for retain.

I recently built a new computer and purchased a copy of Widows 10 and Office 2016.   So far I have tried Mail with Windows 10, Outlook and finally went out on the web and download a copy of Windows Live Mail 2012 (same as on my old computer running Windows 7).  I was able to transfer my emails and contacts by using the tools in Windows 10.  However, the additional support folders with the vital genealogical emails did not transfer.  I have searched the web to see how to do this with no answer.  

My question is how to transfer (export/import) these additional support folders from my old computer using Windows Live Mail 2012 to my new computer using Windows Live Mail 2012 or to the Mail program that came with Windows 10, or Outlook that came withy Office 2016?  I prefer the look and feel of windows Live Mail.