Mozilla Thunderbird 17.0.7

Mozilla Thunderbird is a cross-platform email and news client developed by Mozilla Foundation. Just as Firefox aims to redefine the web browser, Thunderbird is a refinement of the mail and news interface. Users often use them both together.

Thunderbird Features
Migration Assistant to help you set up Thunderbird the way you want it.
One-click Address Book is a quick and easy way to add people to your address book.
The new attachment reminder looks for the word attachment (and other words like file types) in the body of your message and reminds you to add an attachment before hitting send.
The Activity Manager records all the interactions between Thunderbird and your email provider in one place.
If you like Firefox's tabbed browsing, you're going to love tabbed email. Tabbed email lets you load emails in separate tabs so you can quickly jump between them.

Thunderbird is flexible to suit your personality, to give you the features you need, and to fit your work style. Change how Thunderbird looks or add as many features as you want.

With Personas, lightweight "skins" allow you to change the look and feel of Thunderbird in an instant. Hundreds of skins are available from the latest movies, famous landmarks, and Japanese tattoos.