Thanks to the efforts of Nekochan forum member nicolas, Mozilla Thunderbird is now available for IRIX.
The other half of the Firebird web browser (SGI's Freeware site has an older version of Firebird - aka Phoenix - available for download), Thunderbird is a new e-mail client which will eventually become part of the standard Mozilla suite.
Two archives are available for download, a packaged tardist which installs to /usr/local/thunderbird with a binary link in /usr/local/bin and a bzip2 compressed tarball which can be extracted anywhere.
I was wondering what the advantages to bzip2 are?
Primarily better compression; for example the thunderbird-0.1a-irix6.5.tar.bz2 archive weighs in at 29.9MB while the same archive compressed with gzip is 35.6MB.