I am using Thunderbird + IMAP. Thunderbird caches messages locally in:
.icedove/asdfgh.default/ImapMail/mail.example.com/
For each IMAP folder, there are files Folder and Folder.msf.
I have noticed, when I delete an email with large attachment, and then delete it from Trash also, than the trash file .icedove/asdfgh.default/ImapMail/mail.example.com/Trash still contains the email (and the attachment). Thus, even though from within Thunderbird it looks as if the message has been deleted (or expunged from trash, or what ever the term is), the message data is still in the trash file (I can see it when I open the Trash file with my text editor)
Can anybody please explain what is happening here? How can I really delete an email?
And I should add that the email has been successfully deleted on the IMAP server. So, Thunderbird has deleted the email on the server, but for some reason still keeps the data in the file.