"While Mozilla Firefox 1.5 had made its debut back on November
29 of 2005, Thunderbird wasn't released until January 12 of this year.
However, packed into Thunderbird, Mozilla's flagship mail client, is an
array of improvements in a multitude of areas. Now implemented in v1.5
is streamlined and automated updates. improved spam control and
security, enhanced RSS and Podcasting abilities, phising detector,
Kerberos Authentication, and spell check as you type. Mozilla
Thunderbird v1.5 is very much worth the download."