Excess whitespace

I get this error message: Unable to create folder…([CANNOT]) Folder contains excess whitespace (Failure). WHY? What to do?

Find the problematic folder and rename it (delete the whitespace) - it should help.

Rename it in eM client or in Gmail?

In eM Client.

Hi all
Thanks for suggestions. Thunderbird has had the same problem with gmail and local folders. I followed the instructions given and the irritating problem disappeared. Happy Christmas all