Import Mail.app Emails

• 1). Launch Mail.app and open the email folder containing messages you want to import. If you want to copy all the messages, hold <ctrl> and press <A>. Click the "File" menu and select "Save As..." from the menu. Navigate to the folder in which you want to save the file you're importing. Choose "Raw Message Source" from the drop-down list and click the "Save" button. This saves these files with the .mbox extension, which Thunderbird can read.
  
  
• 2). Open Thunderbird and install the ImportExportTool or MboxImport extension to import the Mbox files you just created in Mail.app. Use your favorite browser to navigate to the website, right click on the file and select "Save As" to download without installing it as a browser extension. In Thunderbird, Click "Tools > Addons > Extensions" and locate the extension file you downloaded. Click the "Open" button and when it appears, select "Install Now." Close and then restart Thunderbird.
  
  
• 3). Add your email account to Thunderbird. Use the account wizard to enter your username, password, email account type and account provider. The default settings for most free email services are accurate, but you may need to make adjustments to the default servers and ports for Thunderbird to send and receive your emails with some providers. If you experience problems, check with your service provider for the correct settings.
  
  
• 4). Click the account from which you want to import your messages in Mail.app and click the "Tools" menu. Click "ImportExportTool" and "Import mbox File." Navigate to the file you created in Step 1 and click the "Open" button.
  
  

Import iCal Calender

• 1). Click the "Tools" menu and select the "Addons" option. Search for "Lightning" in the search field. When it comes up, click the "Install in Thunderbird" button.
  
  
• 2). Open iCal, click the "File" menu and select "Export." Save the file to your desktop.
  
  
• 3). Click the "Events and Tasks" menu in Thunderbird and click "Import." Select "iCalender" from the file type drop-down list and navigate to the ICS file you saved to your desktop. Double click it and import your calender.