Форум поддержки Thunderbird

Could not find anything in add-ons, settings, or about:config. There is a topic on this site https://support.mozilla.org/en-US/questions/1086884 but I am not able to follow it because there is no add-on or plugin to enable or I cannot find it.

Hello Folks I recent times we had to migrate from one company to another as the former company no longer provided the emailing service... At first it worked OK...then I was no longer able to get emails and the new company took me through and reset Thunderbird setup,,,once that was done all my folder structure disappeared, and all the info stored in the folders... I have been trying to sort it out, but the company has not been able to do so...and today they suggested to contact Thunderbird to see if they could help... Thank you in anticipation Franco

In the attached screen shot they are two type of folders - One is yellow and looks like a paper folder and the others are rectangular in shape in different colors (here in res and purple) . I am unable to delete the rectangular folder that appear permanent and I don't even know how it was created as I used the same command "new folder" under the inbox or "new subfolder" under a yellow folder - I hope that this is clear : I want to delete the rectangular folders when needed