Firefox uses wrong app for mailto: links

On an XP system: When Firefox fails to regard Thunderbird the “Default Mail Application” (even though you set that elsewhere) the problem may be solved by:

  •  Opening the Control Panel
  • Opening the Folder Options
  • On the File Types tab, find the  (None) URL:MailTo entry
  • Click the Advanced button
  • In the Actions window, you should see the entry: open
  • Click the Edit… button
  • Set the Application Used to Perform Action to the correct path of your Thunderbird as:

“C:\Program Files\Mozilla Thunderbird\thunderbird.exe” -compose “%1″