Create a new profile and copy the old one over it. http://kb.mozillazine.org/Moving_your_profile_folder_-_Thunderbird#Create_a_new_profile_and_copy_the_old_one_over_it

Hello christ1 and many thanks for your quick reply. I have downloaded Thunderbird in the new computer and am in the process of installing it. I have one basic question: Thunderbird is asking me to configure an e-mail account and I don't know if I should skip this step or not. In my previous computer I used three e-mail accounts that were all downloaded to my computer. Is this information in my profile folder or should I input the data of one of the accounts now? Thanks again.

You don't need to set up the account on the new computer. The idea is to copy over the profile as per the instructions, so everything should be there on the new computer after that. You don't need to create a new profile on the new computer either, Thunderbird did that for you already.

christ1 thanks again for the quick reply. In your previous answer you had suggested that I should create a new profile and therefore I was going to follow the directions under the section "Create a new profile and copy the old one over it". In you last last post you mentioned that I don't need to create a new profile in the new computer either. Should I then follow the instructions under the section "Modify profiles.ini to point to the new location"? Thank you.

You follow the instruction as per the article section 'Create a new profile and copy the old one over it'. Just skip over steps 1 through 3 and continue with step 4.

You don't do anything from the 'Modify profiles.ini to point to the new location' section.

christ1, your solution worked, many thanks again for your help!