Lightning makes Thunderbird soar above Outlook for home use, and places it on nearly equal ground in the office. It includes an overhauled interface with easy-to-use buttons for jumping from your mail to your calendar, LDAP directory support for event invites, and Sun Java Calendar Server support.
A menu bar for switching between mail and calendar views can live either above or below the folder tree on the left. On the right side of the main pane is a new panel for quickly viewing and managing events and tasks. Option-heavy, it can show only events, only tasks, both, or hide the pane completely, as well as make changes to and create new events and tasks.
Events are searchable at the calendar top. Just below it is a hideable pane showing upcoming events in a spreadsheet format. There are built-in presets for the next seven, 14, and 31 days, and they can be arranged by start date, end date, title, location, and calendar. Lightning supports multiple calendars, including iCal, and has bidirectional support for Google Calendar with the Provider for Google Calendar plug-in.
There is also some support for Exchange servers. If you receive an invite from somebody using an Exchange server, responding works fine. However, the next time you restart Thunderbird, the calendar will jump the time of the event. Going back and changing it clears up the problem. Despite this hang-up, Lightning is an excellent plug-in for Thunderbird users, both lightweight and robust with features.