Problems with File Management since transferring to Thunderbird. Intro. I have just started to use Thunderbird to access my emails. Prior to that I used Windows Live Mail with the box ticked to keep the email on the server. This let me download and save to my hard drive on my Acer machine. At the same time a separate person in the household using a Toshiba computer – and using the same POP broadband provider - downloaded and saved emails to hard drive by opening Yahoo.com and clicking the EMAIL selection button. Both computers could manage their folders and files separately without interfering with the other. The same emails could be saved separately on each computer and deleting an email on one computer left the file available for the other to see. However since moving to Thunderbird on the Acer and retaining the Yahoo link on the Toshiba if a file is deleted from either computer then it also disappears from the other. Also transferring a file from the INBOX to any folder on either computer causes it to disappear from the other. Both computers are using Windows 10. Questions. Why should this happen as I understand that Thunderbird uses IMAP format which keeps files available on the server? Also are my new Thunderbird files safely stored on my hard drive or will they disappear from my computer if they are ever deleted from the server by the server owner for any reason? Thank you