The last time I relied on email software for personal messaging, George W. Bush was starting his second term, Pluto was still a planet and the Motorola Razr was America's most popular mobile phone.

I embraced Web email a year after Google's Gmail came along in 2004. Until then, Web email had been inferior to stand-alone desktop programs. Gmail's revolutionary approach to email prompted rivals to innovate. As a result, Web email now surpasses desktop software in many ways, particularly as people want their digital lives to travel with them as they connect from multiple devices and locations.

So I was skeptical when a new version of Mozilla's Thunderbird came along. I had all but abandoned it years ago. I was surprised to see how much had changed and improved when I gave Thunderbird a fresh look.

Although it took me a while to get used to, I'm a big fan of Gmail's way of grouping related messages into conversations. Before, you could group related messages into threads, an approach Thunderbird still uses. But messages you receive end up in one folder, and your replies are in another. With Gmail's conversations, it's all together in one stream, arranged chronologically regardless of who wrote what.

I've found that I can stay on top of communications more easily with Gmail's approach, because I can see at a glance which messages I still need to read and reply to. The old way seems cluttered and awkward.

I can also dispose of entire conversations I'm bored with more quickly -- with a single click of the trash icon. Deleting messages one by one seems so last century.

Thunderbird doesn't support conversations, but it offers many other features that make it better than Web mail. Made by the same organization behind the popular Firefox browser, Thunderbird makes checking email almost as...