Thunderbird
From Hackepedia
If you have to enter the password for your email account(s) every time you start Mozilla Thunderbird, you can open your prefs.js file
$ find ~ -name prefs.js | grep thunderbird
to find the file. open it, and modify the line that says:
user_pref("signon.rememberSignons", false);
and change false to true. Now start thunderbird again and you should be set.
I had an issue where thunderbird kept showing me 3 new messages in one folder, but when I clicked on that folder, there was nothing new. The next time I looked at thunderbird, it said 3 new messages in that folder again. What I did was right click on the folder, and chose both
Mark Folder Read Compact This Folder