What is Thunderbird ? Thunderbird is a software that will help your emailing activity  safer, faster and easier than ever. Features from Thunderbird, intelligent spam filters, a built-in spell checker, extension support, and much more.

What is Gmail Drive? this free software is a virtual filesystem on top of your Google GMail account and enables you to save and retrieve files stored on your GMail account directly from inside Windows Explorer.. So with gmail drive you can easily copy files to your GMail account and retrieve them again. When you create a new file using GMail Drive, it generates an e-mail and posts it to your account.

Firefox extension that will allow you to receive email messages, write and read them in your browser
Simple Mail is an extension that will notify, let you read and write email messages in your Firefox browser.

Usage:
Configure one or more accounts in Preferences, set account refresh time and get notified of new mail. When new mail arrives, Simple Mail shows new messages count in status bar. You can click Simple Mail icon to open received messages in a separate browser tab.

Gmail is supported. To use Simple Mail with a Gmail account you should first enable POP in your Gmail preferences (using Gmail web interface), and then configure Simple Mail account with these settings: http://mail.google.com/support/bin/answer.py?answer=13287.

Note: you can’t delete Gmail messages from server using Simple Mail, you can only specify to an option to delete messages using web Gmail interface.

You can use the
following keys to manage messages:
· Insert – select messages
· *, Ctrl-A – select all messages
· Del – delete selected messages

Address Book: When you send a message, Simple Mail saves email addresses of the recepients, so that next time you don’t have to type them again. As you begin typing recepient addresses for the nex time, a drop-down list of available addresses is shown. For example if you previously sent an email to John Smith , you can type “j” to see all addresses beginning with “j” or “j s” for all addresses with first names beginning with “j” and last names beginning with “s”.

Not supported:
· Sending of attachments isn’t currently supported.
· multipart/related content type isn’t shown correctly: images are shown at the end of a letter, not in the middle of message text