Mozilla Messaging has release an emergency third update for Thunderbird 3.0 on all platforms. This release fixes an issue with mail folders for some users who updated to Thunderbird 3.0.2.
Thunderbird 3.0 users should be prompted to update within the next 48-hours or can do so manually via Help >> Check For Updates… For information as to what’s new, see Thunderbird release notes
Source: Mozilla Developers News
