re :'' I can't send an email or receive emails,'' that's because you have not connected to server by entering password at prompt. So that is correct. re :''the emails that have been downloaded are viewable.'' That is correct because they are downloaded and stored on the computer. re:''This isn't a secure option for someone using a shared PC. '' If you are sharing a computer then each person should be using their own 'User Account'. This is the standard normal procedure for anyone regardless of whether there are one or more people using a computer as it seriously improves security. User Accounts can use a password to open to show your desktop. Thunderbird would run from your desktop. Without knowing the 'User Account' password no one can access your desktop nor see any emails. Thunderbird profile folders contain all your mail accounts and emails etc. They would be stored within the User Account. re: ''Is it a bug?'' No.