From Mozillazine.org:

Asa Dotzler writes: "After months of discussion and further months of legal investigation, we're finally comfortable moving forward with new names. The new name for the Phoenix browser is 'Firebird'. The documentation and product strings will be updated soon. In addition to securing Firebird, we've also got the OK from those contributing legal resources to use the name 'Thunderbird' for a mail client. Hopefully this will be the end of naming legal issues for a while."

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