Thunderbird:Extension Frequently Asked Questions
Note: Please continue to update and add more items to this list as questions are asked and answered in the news group
Can a new column be added to the message list view?
Can .eml files on disk be added to the Inbox, or other folders?
Not directly, but you could use nsIMsgFolder::AddMessage(in string aMessage)
Local messages require that you add an envelope header to the beginning of the message (e.g., "From - 01/01/2008"). But you could simply read the .eml file into a string, insert "From " at the beginning of the message, and call AddMessage.