Upgrade notice for "Thunderbird" should not be sent to the "Thunderbird Portable" users.
I switched from the regular "Thunderbird 2.0.0.6" to "Thunderbird Portable 2.0.0.6" a few months ago, then I received an upgrade notice to 2.0.0.9. I first thought it would be for "Thunderbird Portable 2.0.0.6," so I clicked [YES] to upgrade, then I happened to think it might have meant for the regular "Thunderbird." I went trhough the forum to try to find out whether the 2.0.0.9 upgrade would be compatible with "Thunderbird Portable 2.0.0.6," and sure enough I found some members were experiencing problems with add-ons.