[Zope] Can't get ZDConfera to send notification email.

Hello, I just installed ZDConfera to try it out, and it works fine, except for that it won't send any reply-notification-emails. I do have a mailhost configured, and I've allowed all roles to "Use Mailhost Services". Has anyone experienced this too, or does anyone have an idea what causes my problems? Sending mail with <dtml-sendmail mailhost="localhost"> works. Ewald Wasscher