Mail PassView is a small password-recovery tool that reveals the passwords and other account details for the following email clients:
Outlook Express Microsoft Outlook 2000 (POP3 and SMTP Accounts only) Microsoft Outlook 2002/2003/2007 (POP3, IMAP, HTTP and SMTP Accounts) Windows Mail IncrediMail Eudora Netscape 6.x/7.x Mozilla Thunderbird Group Mail Free Yahoo! Mail - If the password is saved in Yahoo! Messenger application. Hotmail/MSN mail - If the password is saved in MSN Messenger application. Gmail - If the password is saved by Gmail Notifier application, Google Desktop, or by Google Talk.
http://www.nirsoft.net/utils/mailpv.html