In my tests of the Windows and Linux versions of the program, I found it to be quicker and far more stable than the 1.0x model.
For Windows, I ran Thunderbird using Windows XP Service Pack 2 on a 3GHz Pentium IV system with 1GB of RAM. For Linux, I used it with SUSE Linux 10 on a 2.8GHz Pentium IV PCs with 512MB of RAM.
To give the program a workout on both platforms, I plowed 10,000 messages through both clients, from a months worth of e-mail via my Qmail SMTP (Simple Mail Transport Protocol) server. Thunderbird handled the load, throwing the spam out, and sorting the messages into a variety of folders without a hitch.
In particular, I noted that the open-source e-mail client was more efficient at handling memory leaks.
I was especially pleased to see that one of my pet peeves, the "This folder is being processed" freeze-up, which had no fewer than six possible causes, no longer appeared.
I also found that Thunderbirds search functionality, which I had eventually abandoned in 1.0x in favor of Google Desktop on Windows and Beagle on Linux, is finally dependable.
In the past, once a mail folder held more than 500 messages, I had found that Thunderbirds search functionality was simply no longer reliable. Now, you can successfully search through folders with more than 1,500 messages.
In a related matter, the program now both properly marks and moves spam messages to a designated folder. In the past, if the new mail folder had too many messages in it, the spam messages would be marked but not moved to the spam folder.
Thunderbird also now handles multiple-SMTP mail transport correctly. In the past, while you could list multiple SMTP servers, the program would actually only use one of them.
Click here to read about Mozillas overhaul of Thunderbirds calendar.
Since mobile users must deal with Internet connections that may or may not let them access remote SMTP network ports, being able to automatically switch from one SMTP server to another on the fly makes sending mail from the road much easier.
The program also now supports global filters. In Thunderbird 1.0, you could set filters to find all messages from, say, your boss, for a given mail account, but not for all your mail accounts. Now you can have all messages from your boss, or what have you, automatically acted on, no matter which account theyve been sent to.
Typically, this functionality is used to automatically send messages to an appropriate mail folder. For example, messages with a subject about cooking to a cooking folder, messages from your boss to a work folder, and so on.
Another new, and increasingly important, feature is Thunderbirds built-in phishing detector. With this, the program automatically marks messages that it considers might be phishing traps. You can then decide whether its a real message from your bank or an attempt to scam you out of your account number.
Thunderbird also now gives you the option of deleting attachments from messages. I find this very handy for getting rid of large PDF files and the like while keeping the cover letter. This new feature, though, is still having teething problems, and has sometimes failed.
The program also has some improvements for enterprise users. The most striking of these is that it now supports Kerberos authentication. However, it still doesnt support either individual or group calendaring.
There are third-party products that do, such as Plaxo Inc.s Thunderbird Toolbar, which adds basic contact management to the program. Unfortunately, it doesnt work with Thunderbird 1.5. Plaxo is, however, expected to support 1.5 after its release.
In its favor, Thunderbird is an e-mail client that you can run on almost any desktop. The program runs on Linux, Windows and Mac OS X. Versions that will run on other platforms, such as Solaris, are also available from groups other than the Mozilla Foundation.
So, if you need groupware functionality with your e-mail, you should still look to Microsoft Corp.s Outlook/Exchange, IBMs Lotus Notes, or Novell Inc.s Evolution client on Linux, with either Exchange or Novell GroupWise in the back room.
If, however, your office just wants a good e-mail client, that doesnt come with Outlooks security risks, then Thunderbird 1.5 will soon be ready for work in your office. It is expected that Thunderbird 1.5 will be released before years end.
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Steven J. Vaughan-Nichols is editor at large for Ziff Davis Enterprise. Prior to becoming a technology journalist, Vaughan-Nichols worked at NASA and the Department of Defense on numerous major technological projects. Since then, he's focused on covering the technology and business issues that make a real difference to the people in the industry.