Right-click still works for me. And I don't understand your issue with folders vs messages.

Try again with the image upload. Until it appears, I have to ask if you are sure that "chem286" is itself a folder and not a message.

If you do right-click it, what options are you shown?

Hi! Thanks for responding. Yes, 'chem286' is itself a folder and not just a message. Within 'chem286' I have another folder 'spring2015' and I would like to add one more. OK. This time the image upload worked. When I R-click on 'chem286' I have the following options: Open in New Tab Open in New Window Search Messages... Delete Rename Compact Mark Folder Read Favorite Folder Properties

Perhaps you can see this in the image file. Perhaps there is some global setting that I used to have turned on, but now it is turned off? ...that allows one to create sub-folders with a R-click? Thank you, Monika

Something seems to be broken, but it's hard to know what.

If you select the Chem286 folder and go to File|New|Subfolder in the menu, does it behave any better?

Are there any messages or other folders named chem286, or some similar variant with different use of capitals? Thunderbird on Windows, in particular, has trouble telling upper and lower case spellings apart, since the underlying OS assumes they are interchangeable.

As an example, if you wanted to rename a folder named important to Important, you'd have to go via an intermediate step, such as as important1, because Windows treats important and Important as interchangeable when used as pathnames, and so it would tell you that there is already a folder with the same name as the one you propose to use.

The weird thing is that when I go to File -> New, I don't get an option to create a subfolder. I'm screenshotting what I get and attaching that.

I don't have any other folders named 'chem286' and this identical thing is happening with ALL my folders. This 'chem286' one was just the simplest one as an example.

I am wondering if somehow my institution disabled this feature (?). Just over a year ago they had everyone on campus switch to Outlook, so now they're supporting Outlook and not Thunderbird. Of course I'm free to use whatever interface I want, though I don't get campus support for it. Still, not being able to organize my e-mail like I did in the past is quite frustrating.

Thanks for helping!

I can not see from those tiny pictures, but is the folder a sub folder of the account or local folders?

Regardless of how your institution locks the account down. You should still be able to use local folder as that is a separate issue.

What add-ons do you have installed? They can cause issues following updates if they are "almost" compatible. Hold the shift key while starting Thunderbird and continue in safe mode when it prompts you. Doe the ability suddenly reappear in safe mode?

I'm not too surprised; the same logic ought to be at work to decide which set of options is offered to you regardless of which route we use to see them. But it was worth a try.

I still don't know what is broken. I don't know of any switch to enable/disenable this function.