I am transferring Thunderbird to a new computer (from pc to MacBook) for my grandmother and I am completely unfamiliar with the program. I was able to transfer the account via thumb drive, but when I try to send an email I am getting a message failed error. As I don't know anything about how Mozilla works and am fairly technologically illiterate, simple guidance would be greatly appreciated! I have tried to make all the settings on the new computer match the old, but am not getting anywhere. TIA!