There is a little trick to the way POP3 email program like Outlook, Outlook Express, Eudora and Thunderbird store the email messages you receive. A “deleted message” is not really deleted! Did you know that?
All your email program does is to rewrite a few characters in the file in order to tell itself that a particular email has been “deleted.”
One particular marking in the file indicates that the email has been deleted, so the program shows it in the Trash folder. A different marking shows it has been deleted from the Trash folder. But, it really has not been removed from the big email.
Read more in Compacting Email Folders
