Mozilla Thunderbird

Features include :

• Advanced Folder Views
  
  Thunderbird offers a variety of ways for you to organize and display your folders, whether by favorites, recently viewed or folders containing unread messages.
• Message Tagging
  Thunderbird allows you to “tag” messages with descriptors such as “To Do” or “Done” or even create your own tags that are specific to your needs. Tags can be combined with saved searches and mail views to make it easier to organize email.
• Message History Navigation
  Thunderbird offers message history navigation that allows you to click “forward” and “back” much like in your Web browser.
• Improved Search
  Thunderbird features a find as you type in the pane that speeds up searches within displayed messages.
• Saved Searches
  Thunderbird allows you to store search criteria as a folder. Rerunning the search is just a matter of clicking on the saved search folder in the folder pane.
• Secure and Protect Your Mail
  Mozilla has bolstered Thunderbird’s acclaimed security and privacy measures to ensure that your communications and identity remain safe. It’s like having your own security guard online.
• Phishing Protection
  Thunderbird protects you from email scams which try to trick users into handing over personal and confidential information by indicating when a message is a potential phishing attempt. As a second line of defense, Thunderbird warns you when you click on a link which appears to be taking you to a different Web site than the one indicated by the URL in the message.
• Cutting Out the Junk
  Mozilla has updated Thunderbird’s popular junk mail folders to stay ahead of spam. Each email you receive passes through Thunderbird's leading-edge junk mail filters. Each time you mark messages as spam, Thunderbird “learns” and improves its filtering so you can spend more time reading the mail that matters. Thunderbird can also use your mail provider's spam filters to keep junk mail out of your inbox.
• Add-ons Manager for Extensions and Themes
  The new Add-ons Manager improves the user interface for managing extensions and themes, making it even easier for you to customize Thunderbird. Install, uninstall, enable and disable your add-ons in a single place.

Many Linux distributions now include a version of thunderbird in their own native package manager format (.rpm, .deb, etc.)

Using Yum to install thunderbird

start a terminal and type the following at the shell prompt:

# yum install thunderbird

Using Apt to install thunderbird

start a terminal and type the following at the shell prompt:

# apt-get install thunderbird
or 
# apt-get install icedove
or 
# sudo apt-get install thunderbird

Using Urpmi to install thunderbird

start a terminal and type the following at the shell prompt:

# urpmi thunderbird

Other Open Source E-Mail clients

• Evolution
• KMail