How good would it be if you could browse the Internet and check your emails without switching applications over and over again. Agreed Thunderbird is a nice option to Microsoft Outlook but what if you can check your emails from Firefox itself?
Simple Mail is a nice little extension for Firefox which will allow you to manage your POP / IMAP accounts to receive emails and also allow you to send out emails with a built in support for SMTP.
Simple Email also has a pretty nice search feature which allows you to search and filter emails as you type. There are some known issues with synchronization with your Gmail IMAP account but hey its Simple Mail so we can live with it for now.
This is definitely a must have Firefox extensions,Email application,POP,IMAP,Firefox Email,Manage Email,Firefox