Comment 90 for bug 222208

Re Postbox: In the Thunderbird dev cycle, we will accept changes that result in failures if users run a modern Thunderbird, and then downgrade to a version of Thunderbird prior to Thunderbird 17. Postbox branched from Thunderbird prior to version 3, and it is unknown how much functionality they have backported. So I would not automatically assume that you could run Thunderbird, then run the same profile on Postbox.