After using Evolution & Outlook, I move to Thunderbird. Definitely it is the best mail client I ever used. However, I tried some of it useful configurable options.
A. Modifying Thunderbird's Reply Header  : By default while replying, you may want to include the date (timestamp). Go to Edit / Tools => Preferences / Options => Advanced => Config Editor => search for "mailnews.reply_header_type" and set it 3.
B. Lightning at Thunderbird 3.0
1. Go to 'Tools -> Add-ons'
2. Click 'Get Add-ons' tab
3. Search for "Lightning" here or at https://addons.mozilla.org/en-US/thunderbird/
4. The results will show "Lightning Nightly Updater (Unofficial)"
5. Install it
6. Restart Thunderbird
7. Go to 'Help -> Check for Latest Lightning Nightly Builds...'
8. Pop-up will show the latest Nightly Build of Lightning which is available
9. Click on Install
10. Restart Thunderbird