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 between email and your calendar, LDAP directory support for event invites, and Sun Java Calendar Server support.
Work on the plug-in is now handled by Mozilla as they prepare to integrate its code into Thunderbird for the big version 3 update coming later this year, but that doesn't mean the plug-in isn't ready for prime-time now. 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 support for Exchange servers, although for enterprise use fans of Thunderbird/Lightning will likely have to talk to their tech support teams to get the servers configured properly. That, of course, is the biggest drawback compared to Outlook. Old bugs relating to timezone management and invitation responses have been eliminated, though, making this add-on an absolute requirement for all users, both at home and in the office.