Hi Romack, It is a bit complicated but here goes. Install Thunderbird. Thunderbird stores all your account settings/messages/address lists in two Profiles folders. You will need these Profiles folders from your old setup or perhaps a recent backup. If you don't have these then I am afraid you cannot get them back. Make backups of these folders and store somewhere safe in case of mishap.

The profiles should be stored here for Windows 10

  C:\Users\(your windows id)\AppData\Roaming\Thunderbird\

and

  C:\Users\(your windows id)\AppData\Local\Thunderbird\

A search for Thunderbird in AppData should find them for different Windows versions. Make sure to show hidden items. For Win 10 open your C:/ folder then click View and put a tick in "Hidden Items".

In the Roaming/Thunderbird folder there are two folders and a config file, Crash Reports, Profiles and profiles.ini, (open the Profiles folder and make a note of the ********.default folder).

   If you have reinstalled Thunderbird before on your old machine 

there may be more than one default folder. Right click each default folder and see which is biggest or navigate to Roaming/Thunderbird/Profiles/********.default/ Use your judgement to select the correct folder.

The Local/Thunderbird folder contains two folders, Profiles and updates.

Open the Local/Thunderbird/Profiles folder and make sure that the

default profile is the same as the one in the Roaming/Thunderbird/Profiles folder. If things have worked it should correspond or at least Be there; it doesn't matter if there is more than one ********.default profile here.

These folders should be copied to your Windows 10 install. It is easier to copy the whole Thunderbird folders over from your old install to the correct folders on Win 10 eg. Roaming and Local. Make sure you put the correct Thunderbird folders in the correct Roaming and Local folders. In my case I renamed them before copying, to ThunderbirdRoaming and ThunderbirdLocal then changed them back when I had copied them over to Win 10. Open Thunderbird then Tools/Account settings. Click on Server Settings and scroll down to the bottom of the window. There should be the title Local Directory: with the box underneath filled in eg. C:\Users....\Roaming\Thunderbird\Profiles\********.default.... Using the Browse button on the right navigate to the Roaming/Thunderbird default profile you noted down earlier then to Mail\pop.mail.xxx.xxx where this is your email provider and select. Untick Automatically download messages and put a tick in the Leave messages on server. This is so you do not lose any new emails. Change to suit your preferences when finished. Restart Thunderbird and all your old emails and account settings should be there. If not, check yoor Accounts/Server Settings page that the correct profile is showing in the Local Directory: box. Hope this helps. Ask for more info if this is as clear as mud! Mark.

Thanks for the good directions... which I understood after reading them several times... all seems to be working well.

Hi Romack, I'm glad I could help. Thanks for letting me know. Mark.

ola, minha página inicial mudou, sabe a linha que dividi ao meio, mensagens e conteúdo das mensagens, esta linha sumiu, e agora esta difícil de ler os e-mai, tenho que dar 2 cliques abrir outra página para so então ler o conteúdo da mensagem.... RESPONDER, ENCAMINHAR E ETC... ALGUÉM SABE COMO VOLTAR AO "NORMAL" OBRIGADA

Oi Marisfbb, Em primeiro lugar, tente pressionar a tecla F8. Mark.