The real problem is that 'vacation' was written in the early 80s and never updated since then. All it needs to do is check the return path for owner-*@* and not reply to such messages. "Precedence: bulk" does not just mean "If you're a vacation program, do not reply to this". It mainly tells unix (sendmail) systems not to deliver the mail unless they have nothing else to do. This is the lowest precedence level besides "junk". In practice it can mean anything from no difference at all to overnight delivery or no delivery at all (timeout before the message gets the opportunity to be delivered). All in all this translates to lower service, not because of a conscious decision by the sendmail administrator but because 90% of people just install the config file that comes with the code and don't try to understand the details, seeing as a sendmail config file looks like random character combinations. So they get the default behaviour, which severely segretates "bulk" traffic. And that's not all. "Precedence: bulk" tells sendmail never to return the mail body when it can't deliver the message (which makes troubleshooting more difficult), and on older versions of sendmail, it means that if there is an error, no delivery error should be returned at all. The party line from the current sendmail manual is that you should use "Precedence: list" to avoid this misfeature. The old sendmails did not recognize the "list" level and thus the breakage will be bypassed. But, of course, 'vacation' doesn't know about "list" since it was introduced in the 90s, so this would not solve the problem. Eric