[imp] invalid folder name - postfix with virtual users

[gt at interad.at]

Hi everybody!

I've installed Horde 3.2 and it works fine, but when i try to create a
folder (or want that the sent mails go to the sent mail folder) I
allways get the error message "invalid folder name".

My MTA is the Postfix, and I work with virtual users(based on MySQL).

Does anybody know what there is to configur?

Thanks, gerwald