Importing Windows Mail (.eml files) into Thunderbird is enabled by the third-party add-on ImportExport Tools. Download and install this add-on to transfer messages from Windows Live Mail to Thunderbird.
1.Export your messages from Windows Mail in .eml format.
2.In Thunderbird, go to Tools | ImportExport | Import eml file.
3.Navigate to the .eml files folder. The default location for Windows Live mail is C:\Users\<username>\AppData\Local\Microsoft\Windows Live Mail (or \Windows Mail).NOTE: To be able to see the folder "App Data" you must first change Folder Options to "Show hidden files, folders, and drives"
4.Select all the .eml files you want to import. To select multiple files, hold down the Ctrl key as you click on each file.
5.Click Open. Your data will be imported.
Importing Windows Mail Contacts
In order to import Windows contacts into Thunderbird, you must export the contacts to a text file (.csv format) and import the file into Thunderbird. See the Import, export, or change the format for contacts article at Microsoft.com for instructions on how to export contacts in Windows 7.
After creating the required file, you can import your contacts using the instructions for importing Outlook 2007 contacts below. However, instead of choosing Outlook in step 3, choose Text file (LDIF, .tab, .csv, .txt) and click Next. In the Select address book file window that appears, select Comma Separated (or All files) in the drop-down list at the bottom right, browse to the .csv file you just created, select it and click Open.
In the Import Address Book window that appears, use the Move Up and Move Down buttons to match the address book fields on the left to the correct data for import on the right, and uncheck items you do not want to import. When you are done, click OK. Your contacts should now be imported and ready for use in Thunderbird.
Note that if you are having problems importing the fields properly (like when all record data to import shows up inside the first field row when inside the Import Address Book window), this is probably a result of an exported .csv file containing semicolons instead of commas, or the other way around. This can happen when, for example, you exported a .csv file using an English Windows version and try to import it into a non-English version of Thunderbird, or in other words, the list (or value) separator in the Windows Regional settings probably does not match the one for the Thunderbird locale. In this case, you should make the list separator match in your Regional settings before exporting the .csv file, or you could edit the already exported .csv file using a text editor and replace all semicolons by commas (or vice versa), and retry the import step.