[otrs] Postmasterfilter failed => where is the mail?

Hi, my PostmasterPOP3.pl claimed "Can't process mail, see log sub system!" I looked up the logs and recognized that I wrote a wrong Postmaster filter: it tried to set a priority which is not available. OK, I corrected the mistake and now all works fine again. But the question I want to ask here: The mail which could not be imported to OTRS seems to be gone - no longer available in any queue. Am I right? Then I worry about a not proper working postmaster filter mechanismn which causes mail-loss until the problem is recognized and corrected. Bye, Alex