I use OS X 10 .10 .5 and every time I start Thunderbird it tries to get Mail from 2 of my email accounts BDL 66@Comcast.net and LLINC 1967@Gmail.com. as soon as it tries to bring those emails down the program immediately freezes and I have to force quit it. I upgraded the program thinking that maybe it would bring those emails down, previously it was not taking any mail password. So I switched over to Macintosh Mail because at least I could download the 3 different email accounts that I have. I have not been able to use Thunderbird for a few months. My wife's computer uses Thunderbird all the time and she has no problems. maybe you can help Dan Haney llinc@comcast.net bdl66@comcast.net llinc1967@gmail.com