The "Integrating amavisd-new with Postfix" guide explains in the beginning how to enable soft_bounce [1]. At my first attempt at following the "Gentoo mailfiltering gateway guide" (in the URL) i failed which resulted in mails bouncing. Had I known about this those mails would probably just have been queued (nothing critical but still..). ;) I think it should be suggested in the beginning of the "Configuring Postfix" section. [1] http://www.ijs.si/software/amavisd/README.postfix.html#requirements_catching_errors
Thanks for reporting; fixed in CVS.