To import an individual message from Thunderbird, select the message and choose File ‣ Save As ‣ File. Save the .eml file into EagleFiler’s To Import folder.
To import whole mailboxes from Thunderbird, make sure that Thunderbird has completely downloaded all the messages and use the Compact Folders command. The POP/local mailboxes are stored in the folder:
/Users/<username>/Library/Thunderbird/Profiles/<profile>/Mail/Local Folders/
(To open the Library folder, go to the Go menu in the Finder and hold down the Option key.) The IMAP mailboxes are stored in the folder:
/Users/<username>/Library/Thunderbird/Profiles/<profile>/ImapMail/
The mailbox files have no extension and can be dragged from the Finder to EagleFiler. The .msf files are not mailboxes and can be ignored or deleted from EagleFiler’s library.
To import an individual message from Thunderbird, use the File ‣ Save As ‣ File command to save the message in Mail Files (.eml) format.