i cannot send mail to my lists any more. the web interface still works, and the listsa are visible, but mail bounces

this is the error message. what can i do?

you can visit the interface at http://sunsite.univie.ac.at/mailman/listinfo

Traceback (innermost last): File "/servers/mailman/scripts/post", line 45, in ? mlist = MailList.MailList(sys.argv[1]) IndexError: list index out of range 554 "|/servers/mailman/mail/wrapper post... unknown mailer error 1