Rated 5 out of 5 stars

Irreplaceable extension without which Thunderbird is just an e-mail client. Lightning is not just a calendar, but also task list and current event schedule in the sidebar. It supports remote calendar - very convenient way to have full e-calendar in Thunderbird, which can be synchronized with the smartphone, tablet or PDA. You must have this extension!

This review is for a previous version of the add-on (1.0b2).