On the one hand, while Thunderbird is a fine replacement for Outlook Express, Eudora or Pegasus Mail, for light e-mail users, the 1.0x versions really failed at handling large jobs (such as 1,000+ e-mail folders).
In addition, the current Thunderbird has problems with memory leaks, search and filtering problems and a variety of bugs ranging from minor to program-stopping.
And, while it is not as vulnerable as Outlook, Thunderbird has had its share of security holes.
Fortunately for its users, the Mozilla Foundation is much faster at fixing the bugs in its programs than Microsoft is at fixing the ones in its software.
As someone who uses multiple platforms, I also am inclined to like Thunderbird because it runs on Linux, Windows and Mac OS.
So it was that Ive been really looking forward to the next major revision of Thunderbird.
Im pleased to say that many of the bugs have now been squashed. In my use of a late version of the beta 1, I found it both faster and far more efficient at handling memory problems.
I also found that its search functionality, which I had eventually entirely abandoned in the 1.0 series in favor of Google Desktop on Windows and Beagle on Linux, is now both dependent and useful.
Another feature, which users on the go will appreciate, is that Thunderbird 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.
Since mobile users have to deal with Internet connections that may or may not let them access SMTP network ports depending upon their addresses, the ability to automatically switch from one SMTP to another makes sending mail from the road much easier.
I found these improvements on both the Windows and Linux platforms.
For Windows, I ran Thunderbird using Windows XP SP 2 on a 3GHz Pentium IV system with 1GB of RAM. For Linux, I used it with SuSE Linux 9.3 and a late beta of SuSE 10 on a pair of 2.8GHz Pentium IV PCs with 512MBs of RAM.
For these improvements alone, Id recommend Thunderbird over Outlook Express and most other individual end user e-mail programs such as Qualcomms Eudora.
However, Thunderbird 1.5 also has many new features. Some of them, such as spell-checking while you type or being able to handle Podcasting, arent very important to me. Others, though, will be important to any user.