NOTE: This tutorial is aimed at Ubuntu users.

  1. Open the home directory
  2. Select you’re username
  3. Press CTRL+H together to reveal hidden files and folders and locate .mozilla-thunderbird and .evolution
  4. Copy everything from ~/.mozilla-thunderbird/zyx.default/Mail into**~/.evolution/mail/local/Inbox.sbd/**  NOTE: Copy only the .mbox files and delete**.**msf files.
  5. Restart Evolution Mail and all you’re mails should be there.

NOTE: This is a short and easy solution if you have lots of folders in Thunderbird.