Sourceforge has changed anything in the mailto procedure so it doesn't work anymore. Please use the mailing list (see support section) directly, sorry.
Here you can directly send any comments to the users mailing list without beeing subscribed. However if you want to get the answer you have to subcribe anyway or regularely check the mailing archive. Please fill in all the fields but obscure your mail address if you don't want spam.
To make your feedback most valuable be as specific as possible. When submitting a bug descriptions don't forget to mention important facts as your operation system (OS), the version number, etc.