First off, let's consider an excerpt from the Mozilla FAQ re: exporting mail files:
Mozilla's mail files are in the standard plain text mbox format, which almost all mail programs can use or import. Many proprietary mail programs have a function to import from Eudora, which also uses the mbox format; this function should read your Mozilla mail files properly.
Your mail files are inside your profile, in the Mail and (if you use IMAP) ImapMail folders. Each mail folder (Inbox, Sent, etc.) is stored as two files – one with no extension (e.g. INBOX), which is the mail file itself (in mbox format), and one with an .msf extension (e.g. INBOX.msf), which is the index (Mail Summary File) to the mail file. Tell the other program to import mail from the file with no extension.
[...]
Full FAQ -
<http://www.mozilla.org/start/1.4/faq/mail-news.html>
Parsing this for your purpose: Boris should locate the MBOX files located in -
c:\documents and settings\jbujes (the user account name may vary).
The files will be in a Mozilla sub-directory of this parent folder. These files can be imported into Thunderbird et. al. (not Firefox, which doesn't sport built-in mail functionality).
Thunderbird is available for download at:
<http://www.mozilla.com/en-US/thunderbird/>
.d.