Sure, I can rename folders, but we shouldn’t need to do that.
I believe this is a limitation of DH’s Mailbox Manager v1.0 client.
Ref this wiki page which says:
Move it to folder
Puts the email in the specified folder. This is possibly the most useful action, but there are a few caveats/restrictions:
The folder must already exist – the filter cannot make the folder for you. If you enter a folder name that does not exist, the emails will be deleted instead of moved. This is not correct anymore. It Does create the folder.
Folder names are cAsE sEnSiTiVe! Double-check your folder name’s spelling and shift key usage.
The filters cannot use folder names that have spaces in the name.
My test: Create a filter for folder my_test. Send email, the filter triggers and a new my_test is created.
Change the folder name to “My Test” with a space, send a similar email, my_test gets re-created.
So I’ll change this to an enhancement request which allows a filter to be created on folders that have a space in the name, since it is valid for folders to have space names.
For my purposes, however, sure, I’ll use folder names that conform to the filter requirements.