Works Like A Champ Rated 4 out of 5 stars
I specifically chose to go with Thunderbird because of the availability of this Add-On. Previously I used Entourage and there was an AppleScript that handled matching up e-mail address's and accounts, but this is far better. My main reason for writing this review is a simple user tip. As most are aware documentation is basically nonexistent for Flexible Identity. I personally don't have a need for the Regular Expression capability but I was losing hair trying to figure out why just putting email address's in the filter sometimes worked and sometimes didn't.
Here is what I found, and I don't consider this a bug by the way, just an idiosyncracy, perhaps due to it's Java roots, I don't know. When you enter an e-mail address in the filter, and you can enter multiple e-mails separated by returns, the very last one CANNOT end with a return. The cursor needs to be at the end of the final email address, not on the line below.
It's easy to get an extraneous return if your cutting and pasting. When there is even just one extraneous return in just one filter, all bets are off as to what is going to happen. Clean up the filters, removing 'hanging returns' and it will work great.
I would have given 5 stars if there was some documentation, but nevertheless, it fulfills a critical need and it works wonderfully!