As soon as you said 'elderly friend', I felt the hairs on the back of my neck stand up. I look over a couple of elderly people's computers and, amongst other things, the amount of times they click-drag folders and files across their email accounts is frightening - with consequences that have me frequently baffled. I'm not sure I'll be able to help but there have been a couple of posts recently where people have complained that functionality has been compromised - and it's become apparent a few posts in that the file structure is something worthy of a horror movie plot. Before someone could help, I think we need a screenshots of the file structure (with any personal info like email addresses) removed. Is this an IMAP or POP account? How many of each? Thunderbird is on a computer?? Which version of Thunderbird are you using? Which Operating System are you using? We can manually delete some folders on the HD but it really needs to be seen what the extent of the problem is first.