I wasn't even aware it had a Mac version but since you and me had no problems with it on X and I have no problems with it on Win, are all those complainers Apple users and should that undermine the otherwise good product? I don't think so.
My experience using thunderbird on linux is that it's a decent mail client, but I've found it corrupts its search index every few months. Rebuilding the index with my mailbox takes several days.
Also, sometimes it'll just not find certain messages. That also means it's time to clear out and rebuild indexes.
This has been my experience every time I use thunderbird, over many years. I'm not sure what it is about my mailbox that makes me see these issues when others don't.
It's a good program but could use some maintenance loving.
