So on one of my mail accounts I have the issue with those phantom folders. I am starting to get crazy over this, since everything I find online is not working for me. What I already tried: * deleting those folders inside Thunderbird (it also deletes the local .msf file, but recreates them on startup) + deleting the global database (following this [https://support.mozilla.org/en-US/kb/rebuilding-global-database official link] ) + deleting the pancea.dat (following a [https://stackoverflow.com/questions/59315775/resolving-the-thunderbird-phantom-folder-issue-gray-italics-folders stackoverflow] thread - only result is, that all folders with special characters (äö etc.) are broken + deleting the .msf folders while Thunderbird was closed and also deleting global database + tried deleting with option "delete immediately" instead of "moving to trash" + tried the option "server does not support subfolders" I made sure no backup/sync programm is conflicting this. I also checked on server side - the folders are not existing on the server, nor are they e.g. in my smartphones mail client. Now I completely deleted the mail account and added it again. The phantom folders are back. So they seem to get synced to the webserver, but are not showing in the webmail interface... Help? ><